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Immunotherapy using immune checkpoint inhibitors (ICIs) has shown superior efficacy compared with conventional chemotherapy in certain cancer types, establishing immunotherapy as the fourth standard treatment alongside surgical intervention, chemotherapy, and radiotherapy. In cancer immunotherapy employing ICIs, CD8‐positive cytotoxic T lymphocytes are recognized as the primary effector cells. For effective clinical outcomes, it is essential that the targeted cancer cells express HLA class I molecules to present antigenic peptides derived from the tumor. However, cancer cells utilize various mechanisms to downregulate or lose HLA class I molecules from their surface, resulting in evasion from immune surveillance. Correlations between prognosis and the integrity of HLA class I molecules expressed by cancer cells have been consistently found across different types of cancer. This paper provides an overview of the regulatory mechanisms of HLA class I molecules and their role in cancer immunotherapy, with a particular emphasis on the significance of utilizing pathological tissues to evaluate HLA class I molecules expressed in cancer cells. [ABSTRACT FROM AUTHOR]

According to the latest evidence, the microbial metabolite Urolithin A (UA), known for its role in promoting cellular health, modulates CD8+ T cell‐mediated antitumor activity. However, the direct target protein of UA and its underlying mechanism remains unclear. Here, this research identifies ERK1/2 as the specific target crucial for UA‐mediated CD8+ T cell activation. Even at low doses, UA markedly enhances the persistence and effector functions of primary CD8+ cytotoxic T lymphocytes (CTLs) and human chimeric antigen receptor (CAR) T cells both in vitro and in vivo. Mechanistically, UA interacts directly with ERK1/2 kinases, enhancing their activation and subsequently facilitating T cell activation by engaging ULK1. The UA‐ERK1/2‐ULK1 axis promotes autophagic flux in CD8+ CTLs, enhancing cellular metabolism and maintaining reactive oxygen species (ROS) levels, as evidenced by increased oxygen consumption and extracellular acidification rates. UA‐treated CD8+ CTLs also display elevated ATP levels and enhanced spare respiratory capacity. Overall, UA activates ERK1/2, inducing autophagy and metabolic adaptation, showcasing its potential in tumor immunotherapy and interventions for diseases involving ERKs. [ABSTRACT FROM AUTHOR]

In this paper, using the methods of killing tumors and impulsive differential equations, two immunotherapy antitumor models for describing therapies of general tumors and advanced solid tumors are established. By using the theories of impulsive equations, small amplitude perturbation techniques, and the comparison technique, we obtain the conditions which guarantee the global asymptotical stability of the tumor‐eliminated periodic solution and system permanence, when immunotherapy alone is performed. The numerical results of the influences of the impulsive perturbation on the inherent oscillation show rich dynamics, such as period‐doubling bifurcation and chaos. Moreover, the effects of the combination of radiotherapy with immunotherapy on antitumor are obtained, including the threshold value of stability conditions of tumor‐eradication periodic solution when the mixed combination treatment of immunotherapy and radiotherapy is performed. Some numerical simulations for the effects of the timing of radiotherapy application and the timing of injection T cells on the threshold value are performed. Finally, we present some theoretical methods for suppressing the growth of tumors. [ABSTRACT FROM AUTHOR]

In this paper, we formulate a within‐host dynamics model for HIV/HTLV‐I co‐infection under the influence of cytotoxic T lymphocytes (CTLs). The model incorporates silent HIV‐infected CD4+T cells and silent HTLV‐infected CD4+T cells. The model includes two routes of HIV transmission, virus to cell (VTC) and cell to cell (CTC). It also incorporates two modes of HTLV‐I transmission, horizontal transmission via direct CTC contact and vertical transmission through mitotic division of Tax‐expressing HTLV‐infected cells. The model takes into account five types of distributed‐time delays. We analyze the model by proving the nonnegativity and boundedness of the solutions, calculating all possible equilibria, deriving a set of key threshold parameters, and proving the global stability of all equilibria. The global asymptotic stability of all equilibria is established by utilizing Lyapunov function and LaSalle's invariance principle. We present numerical simulations to justify the applicability and effectiveness of the theoretical results. In addition, we discuss the effect of HTLV‐I infection on the HIV dynamics and vice versa. [ABSTRACT FROM AUTHOR]

In this paper, the dynamics of stochastic human T‐cell leukemia virus type I (HTLV‐I) infection model with cytotoxic T lymphocyte (CTL) immune response is investigated. First, we show that the stochastic model exists as a unique positive global solution originating from the positive initial value. Second, we demonstrate that the stochastic model is stochastically permanent and stochastically ultimately bounded for any positive initial value. Third, we establish sufficient conditions for the existence of ergodic stationary distribution of the stochastic model. Fourth, the threshold R0∗ between extinction and persistence of the virus is obtained. Finally, numerical simulations are carried out to illustrate the theoretical results. [ABSTRACT FROM AUTHOR]

A two‐dimensional tumor‐immune model with the time delay of the adaptive immune response is considered in this paper. The model is designed to account for the interaction between cytotoxic T lymphocytes (CTLs) and cancer cells on the surface of a solid tumor. The model considers the surface growth as a major growth pattern of solid tumors in order to describe the existence of necrotic kernels. The qualitative analysis shows that the immune‐free equilibrium is unstable, and the behavior of positive equilibrium is closely related to the ratio of the immune killing rate to tumor volume growth rate. The positive equilibrium is locally asymptotically stable when the ratio is smaller than a critical value. Otherwise, the occurrence of the delay‐driven Hopf bifurcation at the positive equilibrium is proved. Applying the center manifold reduction and normal form method, we obtain explicit formulas to determine the properties of the Hopf bifurcation. The global continuation of a local Hopf bifurcation is investigated based on the coincidence degree theory. The results reveal that the time of the adaptive immune system taken to response to tumors can lead to oscillation dynamics. We also carry out detailed numerical analysis for parameters and numerical simulations to illustrate our qualitative analysis. Numerically, we find that shorter immune response time can lead to longer patient survival time, and the period and amplitude of a stable periodic solution increase with the increasing immune response time. When CTLs recruitment rate and death rate vary, we show how the ratio of the immune killing rate to tumor volume growth rate and the first bifurcation value change numerically, which yields further insights to the tumor‐immune dynamics. [ABSTRACT FROM AUTHOR]

Immunotherapy targeting PD‐L1 is still ineffective for a wide variety of tumors with high unpredictability. Deploying combined immunotherapy with alternative targeting is practical to overcome this therapeutic resistance. Here, the deficiency of serine‐threonine kinase STK24 is observed in tumor cells causing substantial attenuation of tumor growth in murine syngeneic models, a process relying on cytotoxic CD8+ T and NK cells. Mechanistically, STK24 in tumor cells associates with and directly phosphorylates AKT at Thr21, which promotes AKT activation and subsequent PD‐L1 induction. Deletion or inhibition of STK24, by contrast, blocks IFN‐γ‐mediated PD‐L1 expression. Various murine models indicate that in vivo silencing of STK24 can significantly enhance the efficacy of the anti‐PD‐1 blockade strategy. Elevated STK24 levels are observed in patient specimens in multiple tumor types and inversely correlated with intratumoral infiltration of cytotoxic CD8+ T cells and with patient survival. The study collectively identifies STK24 as a critical modulator of antitumor immunity, which engages in AKT and PD‐L1/PD‐1 signaling and is a promising target for combined immunotherapy. [ABSTRACT FROM AUTHOR]

A key phenomenon in cancer is the establishment of a highly immunosuppressive tumour microenvironment (TME). Despite advances in immunotherapy, where the purpose is to induce tumour recognition and hence hereof tumour eradication, the majority of patients applicable for such treatment still fail to respond. It has been suggested that high immunological activity in the tumour is essential for achieving effective response to immunotherapy, which therefore have led to exploration of strategies that triggers inflammatory pathways. Here activation of the stimulator of interferon genes (STING) signalling pathway has been considered an attractive target, as it is a potent trigger of pro‐inflammatory cytokines and types I and III interferons. However, immunotherapy combined with targeted STING agonists has not yielded sustained clinical remission in humans. This suggests a need for exploring novel adjuvants to improve the innate immunological efficacy. Here, we demonstrate that extracellular vesicles (EVs), derived from activated CD4+ T cells (T‐EVs), sensitizes macrophages to elevate STING activation, mediated by IFNγ carried on the T‐EVs. Our work support that T‐EVs can disrupt the immune suppressive environment in the tumour by reprogramming macrophages to a pro‐inflammatory phenotype, and priming them for a robust immune response towards STING activation. [ABSTRACT FROM AUTHOR]

Effective vaccines have reduced the morbidity and mortality caused by severe acute respiratory syndrome coronavirus‐2 infection; however, the elderly remain the most at risk. Understanding how vaccines generate protective immunity and how these mechanisms change with age is key for informing future vaccine design. Cytotoxic CD8+ T cells are important for killing virally infected cells, and vaccines that induce antigen‐specific CD8+ T cells in addition to humoral immunity provide an extra layer of immune protection. This is particularly important in cases where antibody titers are suboptimal, as can occur in older individuals. Here, we show that in aged mice, spike epitope–specific CD8+ T cells are generated in comparable numbers to younger animals after ChAdOx1 nCoV‐19 vaccination, although phenotypic differences exist. This demonstrates that ChAdOx1 nCoV‐19 elicits a good CD8+ T‐cell response in older bodies, but that typical age‐associated features are evident on these vaccine reactive T cells. [ABSTRACT FROM AUTHOR]

Background: Bladder cancer (BLCA) is one of the most diagnosed cancers in humans worldwide. Recently, immunotherapy has become a main treatment option for BC. However, most BLCA patients do not respond to immune checkpoint inhibitors or relapse after immunotherapy. Therefore, it is very important to identify novel biomarkers for the prediction of immunotherapy response in B patients. Methods: Pancancer single‐cell RNA sequencing (scRNA‐seq) data were used to identify the clusters of CD4+ T cells in the tumour microenvironment (TME). The clinical significance of key CD4+ T‐cell clusters was evaluated based on the survival data of two independent immunotherapy bladder cancer (BLCA) cohorts. We also investigated the function of key clusters of CD4+ T cell in the TME of BC cells in vitro. Results: This study identified two novel exhausted CD4+ T‐cell subpopulations with the expression of PD1hi CD200hi or PD1hi CD200low in BC patients. Moreover, BLCA patients with a high level of PD1hi CD200hi CD4+ exhausted T cell showed immunotherapy resistance. Cell function analysis demonstrated that PD1hi CD200hi CD4+ exhausted T cell can promote epithelial–mesenchymal transition (EMT) and angiogenesis in BLCA cells. In addition, PD1hi CD200hi CD4+ exhausted T cells were shown to communicate with malignant BLCA cells through the GAS6–AXL axis. Finally, we also found that GAS6 expression is upregulated in B cells by METTL3‐mediated m6A modification. Conclusions: PD1hi CD200hi CD4+ exhausted T cell may serve as a novel biomarker for poor prognosis and immunotherapy resistance in B. Targeted inhibitors of PD1hi CD200hi CD4+ exhausted T cells may help improve the efficacy of immunotherapy. [ABSTRACT FROM AUTHOR]

Materials‐based antigen delivery systems can augment the immune response by improving antigen uptake in antigen‐presenting cells, targeting lymph nodes, prolonging antigen exposure, enhancing cross‐presentation, etc. Recent research revealed that some antigen carriers activate the innate immune pathways without additional adjuvant. Here, a vaccine delivery platform (antigen nanocapsules) constructed by a one‐step in situ polymerization is reported, weaving a biodegradable polymer network around the antigen surface. This simple technology allowed us to study the immunomodulatory effect of various antigen carriers. An antigen nanocapsule (NC7) capable of inducing dendritic cell activation and cross‐presentation is identified. Further mechanistic studies revealed that NC7 activated the cGAS‐STING pathway in a cGAS‐dependent manner. Moreover, the subcutaneously injected NC7 accumulated in the lymph nodes and elicited strong cytotoxic T cell immunity and T cell memory against established cancer. Collectively, the often‐neglected immunomodulatory effect of various cationic antigen carriers, enabling potential application in cancer vaccines, is uncovered. [ABSTRACT FROM AUTHOR]

Distinct thermal therapies have been used for cancer therapy. For hyperthermia (HT) treatment the tumour tissue is heated to temperatures between 39 and 45°C, while during ablation (AB) temperatures above 50°C are achieved. HT is commonly used in combination with different treatment modalities, such as radiotherapy and chemotherapy, for better clinical outcomes. In contrast, AB is usually used as a single modality for direct tumour cell killing. Both thermal therapies have been shown to result in cytotoxicity as well as immune response stimulation. Immunogenic responses encompass the innate and adaptive immune systems and involve the activation of macrophages, dendritic cells, natural killer cells and T cells. Several heat technologies are used, but great interest arises from nanotechnology‐based thermal therapies. Spontaneous tumours in dogs can be a model for cancer immunotherapies with several advantages. In addition, veterinary oncology represents a growing market with an important demand for new therapies. In this review, we will focus on nanoparticle‐mediated thermal‐induced immunogenic effects, the beneficial potential of integrating thermal nanomedicine with immunotherapies and the results of published works with thermotherapies for cancer using dogs with spontaneous tumours, highlighting the works that evaluated the effect on the immune system in order to show dogs with spontaneous cancer as a good model for evaluated the immunomodulatory effect of nanoparticle‐mediated thermal therapies. [ABSTRACT FROM AUTHOR]

Afterward, N SB 52-59 sb -specific T cells were fluorescence-activated cell sorting-based isolated from the spleen and transferred to new hosts bearing the CD45.2 genetic marker, to facilitate discrimination between transferred antigen-specific T cells and I de novo i -generated host antigen-specific T cells. Keywords: adaptive immunity; immune memory; memory T-cell; T-cell EN adaptive immunity immune memory memory T-cell T-cell 374 376 3 05/03/23 20230501 NES 230501 T-cell memory is considered long-lasting, but new evidence recently published in I Nature i by Soerens I et al i . shows that, under certain conditions, mouse memory T-cell immunity can span several mouse lifetimes. Age is just a number: long-lasting T-cell immunity can span several lifetimes. [Extracted from the article]

Inosine is proven to promote the proliferation and function of CD8+ cytotoxic lymphocytes (CD8+ T) under glucose restriction and enhance the efficacy of programmed cell death protein ligand‐1 (PD‐L1) blockade therapy. However, systemic administration of high frequencies and large doses of inosine and anti‐PD‐L1 antibody (aPDL1) is required, which inevitably reduces bioavailability and causes severe immunological side effects. Therefore, it is crucial to develop a drug delivery system to achieve gradient release of inosine and aPDL1 for local immunotherapy. In this study, an inosine‐based supramolecular hydrogel, inosine‐phenylenediboronic‐isoguanosine (IPBisoG), is successfully developed following a simple one‐pot procedure. Both in vitro and in vivo studies demonstrate that the biocompatible and biodegradable IPBisoG hydrogel displays excellent stability and self‐healing properties. Furthermore, the IPBisoG hydrogel is shown to achieve the gradual and sequential release of inosine and aPDL1. Inosine, which enhances the proliferation and function of CD8+ T cells, together with aPDL1, the blocker of the immunosuppressive pathway in tumor microenvironment, can highly enhance the in vivo efficacy of PD‐L1 blockade therapy. The employment of IPBisoG hydrogel is also shown to trigger systemic immune responses. These results demonstrate that IPBisoG hydrogel can be a promising platform for tumor‐local immunotherapy in the future. [ABSTRACT FROM AUTHOR]

Inadequate β‐cell mass is essential for the pathogenesis of type 2 diabetes (T2D). Previous report showed that an immunomodulator FTY720, a sphingosine 1‐phosphate (S1P) receptor modulator, sustainably normalized hyperglycemia by stimulating β‐cell in vivo regeneration in db/db mice. We further examined the effects of FTY720 on glucose homeostasis and diabetic complications in a translational nonhuman primate (NHP) model of spontaneously developed diabetes. The male diabetic cynomolgus macaques of 18–19 year old were randomly divided into Vehicle (Purified water, n = 5) and FTY720 (5 mg/kg, n = 7) groups with oral gavage once daily for 10 weeks followed by 10 weeks drug free period. Compared with the Vehicle group, FTY720 effectively lowered HbA1c, blood concentrations of fasting glucose (FBG) and insulin, hence, decreased homeostatic model assessment of insulin resistance (HOMA‐IR); ameliorated glucose intolerance and restored glucose‐stimulated insulin release, indicating rejuvenation of β‐cell function in diabetic NHPs. Importantly, after withdrawal of FTY720, FBG, and HbA1c remained at low level in the drug free period. Echocardiography revealed that FTY720 significantly reduced proteinuria and improved cardiac left ventricular systolic function measured by increased ejection fraction and fractional shortening in the diabetic NHPs. Finally, flow cytometry analysis (FACS) detected that FTY720 significantly reduced CD4 + and CD8 + T lymphocytes as well as increased DC cells in the circulation. Immunomodulator FTY720 improves glucose homeostasis via rejuvenation of β‐cell function, which can be mediated by suppression of cytotoxic CD8 + T lymphocytes to β‐cells, thus, may be a novel immunotherapy to reverse T2D progression and ameliorate the diabetic complications. [ABSTRACT FROM AUTHOR]

SPHK1 (sphingosine kinase-1) catalyzes the phosphorylation of sphingosine to sphingosine-1-phosphate (S1P), is found to be highly expressed in solid tumors. Here, extracellular vesicles (EVs) are identified as the key transporters of SPHK1 to the tumor microenvironment. Consequently, SPHK1-packaged EVs elevate S1P levels in the tumor microenvironment, where S1P appears as an immunosuppressive agent. However, the exact mechanism of how S1P mediates its immunosuppressive effects in cancer is not understood. It is investigated that S1P can induce T cell exhaustion. S1P can also upregulate programmed death ligand-1 (PDL-1) expression through E2F1-mediated transcription. Notably, an SPHK1 inhibitor PF543 improves T cell-mediated cytotoxicity. Furthermore, combining PF543 with an anti-PD-1 antibody reduces tumor burden and metastasis more effectively than PF543 alone in vivo. These data demonstrate a previously unrecognized mechanism of how SPHK1-packaged EVs contribute to the progression of ovarian cancer and thus present the potential clinical application of inhibiting SPHK1/S1P signaling to improve immune checkpoint blockage (anti-PD-1 antibody) therapy in ovarian cancer. [ABSTRACT FROM AUTHOR]

The pathogenic immune response in celiac disease (CeD) is orchestrated by phenotypically distinct CD4+ T cells that recognize gluten epitopes in the context of disease‐associated HLA‐DQ allotypes. Cells with the same distinct phenotype, but with elusive specificities, are increased across multiple autoimmune conditions. Here, whether sorting of T cells based on their distinct phenotype (Tphe cells) yields gluten‐reactive cells in CeD is tested. The method′s efficiency is benchmarked by parallel isolation of gluten‐reactive T cells (Ttet cells), using HLA‐DQ:gluten peptide tetramers. From gut biopsies of 12 untreated HLA‐DQ2.5+ CeD patients, Ttet+/Tphe+, Ttet−/Tphe+, and Ttet−/Tphe− cells are sorted for single‐cell T‐cell receptor (TCR)‐sequencing (n = 8) and T‐cell clone (TCC)‐generation (n = 5). The generated TCCs are TCR sequenced and tested for their reactivity against deamidated gluten. Gluten‐reactivity is observed in 91.2% of Ttet+/Tphe+ TCCs, 65.3% of Ttet−/Tphe+ TCCs and 0% of Ttet−/Tphe− TCCs. TCR sequencing reveals clonal expansion and sequence sharing across patients, features reflecting antigen‐driven responses. The feasibility to isolate antigen‐specific CD4+ T cells by the sole use of phenotypic markers in CeD outlines a potential avenue for characterizing disease‐driving CD4+ T cells in autoimmune conditions. [ABSTRACT FROM AUTHOR]

Background: Maintenance with "everolimus + reduced dose tacrolimus" (Ev + Taclow) was reported to reduce the risk of viral infections compared to "tacrolimus + mycophenolate mofetil" (Tac + MMF). Here we examined viremia and viral‐specific T‐cell (viral‐Tc) responses in patients treated with Ev + Taclow versus Tac + MMF in highly‐human leukocyte antigen (HLA)‐sensitized patients. Methods: HLA‐sensitized (HS) kidney transplant patients were monitored pre‐ and post‐transplant for viremia (cytomegalovirus (CMV), BK, and Epstein–Barr virus (EBV)) by polymerase chain reaction (PCR) in 19 Ev + Taclow and 48 Tac + MMF patients. For CMV PCR analysis, we compared infection rates in 19 Ev + Taclow patients to 48 CMV D+/R‐ (#28) or CMV D‐/R‐ (#20) Tac + MMF patients. CMV‐specific cytotoxic T cell (CMV‐Tc) and EBV‐specific cytotoxic T cell (EBV‐Tc) were evaluated by cytokine flow cytometry, and donor‐specific antibody (DSA) levels by Luminex for selected patients in both groups. Results: CMV and EBV viremia rates were similar in Ev + Taclow versus Tac + MMF patients, but BK virus (BKV) rates were significantly higher in Ev + Taclow patients. No patient in either group developed BK virus‐associated allograft nephropathy (BKAN) or post‐transplant lymphoproliferative disorders (PTLD). CMV‐Tc and EBV‐Tc decreased significantly after alemtuzumab induction but returned to pre‐treatment levels 1–2 months post‐transplant in most patients. de novo DSA was similar in both groups as were patient and graft survival and graft rejection. Conclusions: CMV‐Tc and EBV‐Tc were similar in Ev + Taclow and Tac + MMF patients. EBV and CMV viremia rates were similar over 1 year. BKV rates were significantly higher in Ev + Taclow patients suggesting no benefit for Ev + Taclow in enhancing viral‐Tc effector functions or limiting viral infections. [ABSTRACT FROM AUTHOR]

T‐cell‐based immunotherapy and immune checkpoint blockade have been successfully used to treat several human solid cancers. The present study attempted to investigate the feasibility and efficacy of the antitumor effect of adoptive cell therapy along with programmed cell death protein 1 (PD‐1) inhibitor on triple‐negative breast cancer (TNBC). Tumor infiltration lymphocytes (TILs) from TNBC mouse tumor tissues were isolated and expanded, and TILs for adoptive cell therapy (TILs‐ACT) were applied in combination with a PD‐1 inhibitor to the TNBC mouse model. The pre‐ and post‐therapy antitumor efficacy, cytokine secretion, and pathological changes were assessed both in vitro and in vivo. We found that TILs exhibited higher IFN‐γ and TNF‐α secretion than conventional T cells. The TILs‐ACT combined with PD‐1 inhibitor promoted active T‐cell infiltration into the tumor tissue and exerted a strong antitumor effect in an in vivo model. Additionally, the strategy could downregulate the expression of inhibitory marker PD‐1 on TILs. In conclusion, PD‐1 blockade regulated T‐cell exhaustion that synergized with adoptive TIL transfer immunotherapy, leading to eradication of established TNBC tumors. These findings might be useful in developing a feasible and effective therapeutic approach for TNBC. [ABSTRACT FROM AUTHOR]

Despite remarkable advances in different types of cancer therapies, an effective therapeutic strategy is still a major and significant challenge. One of the most promising approaches in this regard is immunotherapy, which takes advantage of the patients' immune system; however, the many mechanisms that cancerous cells harbor to extend their survival make it impossible to gain perfect eradication of tumors. The response rate to cancer immunotherapies, especially checkpoint inhibitors and adoptive T cell therapy, substantially differs in various cancer types with the highest rates in advanced melanoma and non‐small cell lung cancer. Indeed, the lack of response in many tumors indicates primary resistance that can originate from either tumor cells (intrinsic) or tumor microenvironment (extrinsic). On the other hand, some tumors show an initial response to immunotherapy followed by relapse in few months (acquired resistance). Understanding the underlying molecular mechanisms of immunotherapy resistance makes it possible to develop effective strategies to overcome this hurdle and boost therapy outcomes. In this review, we take a look at immunotherapy strategies and go through a number of primary and acquired resistance mechanisms. Also, we present various ongoing methods to overcoming resistance and introduce some promising fields to improve the outcome of immunotherapy in patients affected with cancer. [ABSTRACT FROM AUTHOR]

Background: Viral infections are controlled primarily by viral‐specific T cells, raising concern for adequate T‐cell response to clear CMV infection in transplant recipients receiving lymphocyte‐depleting agents (LDA). We examined the rates of CMV viremia and clearance, seroconversion, and CMV‐specific CD8+ T cell (CMV‐Tc) activity with class of induction agent received. Methods: Retrospective review of 45 pediatric renal transplant recipients who received induction with LDA (n = 31) or non‐LDA (NLDA; n = 14) received valganciclovir prophylaxis for 6 months post‐transplant and CMV‐PCR monitoring. CMV‐Tc was measured by intracellular IFNγ flow cytometry, when possible, at baseline, 1 month after CMV viremia (>5 copies/PCR) and serially until CMV‐Tc was positive (≥0.2%). Results: Viremia rates at 1, 2, and 4 years post‐transplant were higher in LDA vs. NLDA (46.3% vs. 7.2%, 64.2% vs. 7.2%, and 64.2% vs. 7.2%, respectively; p =.002). Viremia rates at these time points in seronegative LDA (50.3%, 71.6%, 71.6%) were significantly or near significantly higher than seronegative NLDA (9.1%, 9.1%, 9.1%; p =.004), seropositive‐LDA (22.3%, 22.3%, 22.3%; p =.07), or seropositive NLDA (0%, 0%, 0%; p =.07). Eleven of 17 (64.7%) viremic subjects required valganciclovir dose reduction during the prophylaxis period for leukopenia. All viremic LDA patients developed CMV‐Tc. One viremic NLDA patient did not develop CMV‐Tc. No patients developed CMV disease. Conclusion: CMV seronegative pediatric renal transplant patients receiving LDA are more likely to have valganciclovir prophylaxis dose reduction and develop subclinical CMV viremia; however, all developed CMV‐Tc. Larger prospective studies are needed to further understand the effects of induction agents on CMV‐Tc and CMV‐Tc's role post‐transplant. [ABSTRACT FROM AUTHOR]

In the tumor microenvironment, T cells, B cells, and many other cells play important and distinct roles in anti‐tumor immunotherapy. Although the immune checkpoint blockade and adoptive cell transfer can elicit durable clinical responses, only a few patients benefit from these therapies. Increased understanding of tumor‐infiltrating immune cells can provide novel therapies and drugs that induce a highly specific anti‐tumor immune response to certain groups of patients. Herein, the recent research progress on tumor‐infiltrating B cells and T cells, including CD8+ T cells, CD4+ T cells, and exhausted T cells and their role in anti‐tumor immunity, is summarized. Moreover, several anti‐tumor therapy approaches are discussed based on different immune cells and their prospects for future applications in cancer treatment. [ABSTRACT FROM AUTHOR]

Summary: Allogeneic immune responses underlie the graft‐versus‐leukaemia effect of stem cell transplantation, but disease relapse occurs in many patients. Minor histocompatibility antigen (mHAg) peptides mediate alloreactive T cell responses and induce graft‐versus‐leukaemia responses when expressed on patient haematopoietic tissue. We vaccinated nine HA‐1‐negative donors against HA‐1 with a 'prime–boost' protocol of either two or three DNA 'priming' vaccinations prior to 'boost' with modified vaccinia Ankara (MVA). HA‐1‐specific CD8+ T cell responses were observed in seven donors with magnitude up to 1·5% of total CD8+ T cell repertoire. HA‐1‐specific responses peaked two weeks post‐MVA challenge and were measurable in most donors after 12 months. HA‐1‐specific T cells demonstrated strong cytotoxic activity and lysed target cells with endogenous HA‐1 protein expression. The pattern of T cell receptor (TCR) usage by HA‐1‐specific T cells revealed strong conservation of T cell receptor beta variable 7‐9 (TRBV7‐9) usage between donors. These findings describe one of the strongest primary peptide‐specific CD8+ T cell responses yet recorded to a DNA–MVA prime–boost regimen and this may reflect the strong immunogenicity of mHAg peptides. Prime–boost vaccination in donors or patients may prove of substantial benefit in boosting graft‐versus‐leukaemia responses. [ABSTRACT FROM AUTHOR]

Oncolytic virotherapies are perceived as remarkable immunotherapies coming into view and represent highly promising cancer treatments, yet to figure out its specific immune responses and underlying barriers remains critical. Albeit recent studies have demonstrated that oncolytic viruses (OVs) could fine tune tumor microenvironment (TME) to elicit tumor suppression mainly due to effective T‐cell responses, the interaction between suppressive T cells and OVs is barely undetermined. Herein, we found that regulatory T cells (Treg cells) were increased in the TME following systemic administration of oncolytic virus M1 along with the higher expression of relative cytokines and chemokines in both mouse RM‐1 prostatic carcinoma model and mouse B16F10 melanoma model. Besides, Treg cells expressed high levels of CD25 post‐M1 treatment, and its suppressive effect on CD8+ T cells was also elevated. Depletion of Treg cells in M1‐treated groups significantly reinforced antitumor effect of M1. Specific targeting of Treg cells using cytotoxic T lymphocyte‐associated protein 4 (CTLA‐4) antibody (Ab) in combination with M1 treatment elicited a more profound tumor suppression and longer overall survival time than M1 alone in both tumor models. Moreover, CTLA‐4 Ab further aggrandized antitumor immune response elicited by M1, including increased infiltration of CD45+ immune cells and CD8+ or CD4+ T lymphocytes, decreased ratio of Treg cells to CD4+ T lymphocytes, the intensified lymphocytotoxicity and elevated secretion of cytotoxic cytokines like interferon‐γ, granzyme B and perforin. Therefore, our findings constituted a suggestive evidence that targeting Treg cells in M1‐based oncolytic virotherapy may achieve a highly response in clinical cancer research. [ABSTRACT FROM AUTHOR]

Solid tumors are protected from antitumor immune responses due to their hypoxic microenvironments. Weakening hypoxia‐driven immunosuppression by hyperoxic breathing of 60% oxygen has shown to be effective in unleashing antitumor immune cells against solid tumors. However, efficacy of systemic oxygenation is limited against solid tumors outside of lungs and has been associated with unwanted side effects. As a result, it is essential to develop targeted oxygenation alternatives to weaken tumor hypoxia as novel approaches to restore immune responses against cancer. Herein, injectable oxygen‐generating cryogels (O2‐cryogels) to reverse tumor‐induced hypoxia are reported. These macroporous biomaterials are designed to locally deliver oxygen, inhibit the expression of hypoxia‐inducible genes in hypoxic melanoma cells, and reduce the accumulation of immunosuppressive extracellular adenosine. The data show that O2‐cryogels enhance T cell‐mediated secretion of cytotoxic proteins, restoring the killing ability of tumor‐specific cytotoxic T lymphocytes, both in vitro and in vivo. In summary, O2‐cryogels provide a unique and safe platform to supply oxygen as a coadjuvant in hypoxic tumors and have the potential to improve cancer immunotherapies. [ABSTRACT FROM AUTHOR]

Immunotherapy targeting the Programmed Death (PD‐1) receptor/ligand (L) "checkpoint" rapidly gains ground in the treatment of many cancer types. To increase treatment scope and efficacy, predictive biomarkers and rational selection of co‐treatments are required. To meet these demands, we must understand PD‐1 function in detail. We here outline recent insights into the regulation of the CD8+ T cell response by PD‐1. The prevailing view has been that blockade of PD‐1/ligand (L) interaction "reinvigorates" cytotoxic T lymphocytes (CTL) that were rendered dysfunctional in the tumor microenvironment (TME). However, this review stresses that tumors continuously communicate with adjacent draining lymph nodes (LNs) and that the PD‐1 checkpoint also operates during T cell priming. We clarify the role of the PD‐(L)1 system at the T cell/DC interface, where it regulates T cell receptor (TCR) signaling and CD28 costimulation and thus controls activation of tumor‐specific T cells. We also highlight the importance of CD4+ T cell help during priming, which allows DCs to provide other costimulatory and cytokine signals required for optimal CTL differentiation and likely avoidance of a dysfunctional state. Therefore, we pose that PD‐(L)1 blockade should exploit LN function and be combined with "help" signals to optimize CTL efficacy. [ABSTRACT FROM AUTHOR]

Following an impressive career of T- and NK cell characterization, Hergen discovered multiple subsets of ILCs in humans and was essential in the realization that (A) the ILC family is a mirror image of the T-cell repertoire in terms of transcriptional requirements and effector functions. Keywords: basic immunology; basic mechanisms; T cells EN basic immunology basic mechanisms T cells 1925 1928 4 06/18/21 20210601 NES 210601 MAJOR CONTRIBUTIONS Discovery of the role of adhesion and CD3 re-directed killing in T cell-mediated cytotoxicity (from 1980) Dissection of the mechanisms of thymic selection in human chimeras (from 1986) Elucidation of the role of IL-4 (from 1987) and IL-10 (from 1991) in immunoregulation Description of human T-, NK-, and dendritic cell ontogeny (from 1990) Immortalization of antigen-specific B cells for clonal production of high-affinity therapeutic antibodies (from 2004) Discovery of human innate lymphoid cell (ILCs) subsets, their differentiation and plasticity (from 2009) Hergen Spits' retirement symposium was held in the Zuiderkerk, Amsterdam, the Netherlands, on 18 February 2019. It did not take long until Hergen had identified the human Th22 subset.3 In addition, Hergen quickly realized that the IL-22 production that he observed in the T-cell system had an equivalent among innate lymphocytes resembling NK cells. [Extracted from the article]

Extracellular vesicles (EVs) mediate the cross‐talk between cancer cells and the cells of the surrounding Tumour Microenvironment (TME). Professional killer cells include Natural Killer (NK) cells and CD8+ Cytotoxic T‐lymphocytes (CTLs), which represent some of the most effective immune defense mechanisms against cancer cells. Recent evidence supports the role of EVs released by NK cells and CTLs in killing cancer cells, paving the road to a possible therapeutic role for such EVs. This review article provides the state‐of‐the‐art knowledge on the role of NK‐ and CTL‐derived EVs as anticancer agents, focusing on the different functions of different sub‐types of EVs. We also reviewed the current knowledge on the effects of cancer‐derived EVs on NK cells and CTLs, identifying areas for future investigation in the emerging new field of EV‐mediated immunotherapy of cancer. [ABSTRACT FROM AUTHOR]

Background/Aim: Biotin is a vital micronutrient that plays a role in metabolic homeostasis and the regulation of innate and adaptive immune system functions. Biotinidase deficiency (BTD) leads to impairment in biotin‐dependent immune functions. This study focused on immunophenotypic analysis of lymphocyte subsets in newborns with BTD. Patients and Methods: A total of 181 (95 female and 86 male; 114 had BTD and 67 were healthy) newborns underwent biotinidase enzyme activity, molecular and lymphocyte immunophenotyping analyses. BTD is classified into four biochemical phenotypes: profound, partial, heterozygous and normal. The following lymphocyte subsets were studied in all participants: total B lymphocyte (CD19), total T lymphocyte (CD3), helper T lymphocyte (CD3/CD4), cytotoxic T lymphocyte (CTL) (CD3/CD8), natural killer T lymphocyte (CD16/56) and a T‐lymphocyte activation marker (HLA‐DR). Results: The percentages of lymphocyte subsets were similar in newborns with and without BTD. In all newborns with BTD, the mean CD3/CD4 levels were higher in females, while the CD3/CD8 levels were higher in males (P <.001 for each). In female and male newborns, the CD3/CD4 levels were 53.83 ± 9.46 and 16.82 ± 5.19, respectively, and the CD3/CD8 levels were 48.80 ± 8.65 and 21.48 ± 6.02, respectively. A moderate negative correlation was found between CD3/CD4 and CD3/CD8 in female and male newborns (rfemale = −0.488, rmale = −0.574, P <.001). Conclusion: This study showed that although there were no differences in the lymphocyte subsets in newborns with BTD, the CD3/CD4 levels were higher in females, and the CD3/CD8 levels were higher in males. In addition, there was a negative correlation between the CD3/CD4 and CD3/CD8 levels in both genders. Although these results indicate sexual dimorphism between CD3/CD4 and CD3/CD8 levels, whether this dissociation is unique to BTD in newborns is not fully clear. [ABSTRACT FROM AUTHOR]

Cold tumors generally show low mutational burden and low infiltration of effector T cells. The pancreas, prostate, ovary, breast, and colon are placed into the category of cold tumors. In such tumors, effector T cells are either excluded from the tumor area or taken away from being in contact with tumor cells. The stromal reaction in the form of desmoplasia is important for the pathogenesis of tumors like the pancreas. Besides acting as a barrier for the penetration of drugs into the tumor area, the dense stroma presumably creates an immunosuppressive tumor microenvironment (TME), which accounts for low responses from tumor to immunotherapy. Cancer stem cells (CSCs) are an important part of the immunosuppressive complex within the TME. The presence of CSCs within the TME is related negatively to the activity of the antitumor immune system. Here, the question is how desmoplastic aggregates can influence the functionality of CSCs for promoting a cold pancreatic tumor immunity? This review is aimed at responding to this question, the disruption of which can be an effective strategy for improving responses from cold tumors to immunotherapy. [ABSTRACT FROM AUTHOR]

Background: SARS‐CoV‐2 has triggered a pandemic that is now claiming many lives. Several studies have investigated cellular immune responses in COVID‐19‐infected patients during disease but little is known regarding a possible protracted impact of COVID‐19 on the adaptive and innate immune system in COVID‐19 convalescent patients. Methods: We used multiparametric flow cytometry to analyze whole peripheral blood samples and determined SARS‐CoV‐2‐specific antibody levels against the S‐protein, its RBD‐subunit, and viral nucleocapsid in a cohort of COVID‐19 convalescent patients who had mild disease ~10 weeks after infection (n = 109) and healthy control subjects (n = 98). Furthermore, we correlated immunological changes with clinical and demographic parameters. Results: Even ten weeks after disease COVID‐19 convalescent patients had fewer neutrophils, while their cytotoxic CD8+ T cells were activated, reflected as higher HLA‐DR and CD38 expression. Multiparametric regression analyses showed that in COVID‐19‐infected patients both CD3+CD4+ and CD3+CD8+ effector memory cells were higher, while CD25+Foxp3+ T regulatory cells were lower. In addition, both transitional B cell and plasmablast levels were significantly elevated in COVID‐19‐infected patients. Fever (duration, level) correlated with numbers of central memory CD4+ T cells and anti‐S and anti‐RBD, but not anti‐NC antibody levels. Moreover, a "young immunological age" as determined by numbers of CD3+CD45RA+CD62L+CD31+ recent thymic emigrants was associated with a loss of sense of taste and/or smell. Conclusion: Acute SARS‐CoV‐2 infection leaves protracted beneficial (ie, activation of T cells) and potentially harmful (ie, reduction of neutrophils) imprints in the cellular immune system in addition to induction of specific antibody responses. [ABSTRACT FROM AUTHOR]

Immunotherapy has revolutionized the treatment of cancer in recent years and achieved overall success and long‐term clinical benefit in patients with a wide variety of cancer types. However, there is still a large proportion of patients exhibiting limited or no responses to immunotherapeutic strategy, some of which were even observed with hyperprogressive disease. One major obstacle restricting the efficacy is that tumor‐reactive CD8+ T cells, which are central for tumor control, undergo exhaustion, and lose their ability to eliminate cancer cells after infiltrating into the strongly immunosuppressive tumor microenvironment. Thus, as a potential therapeutic rationale in the development of cancer immunotherapy, targeting or reinvigorating exhausted CD8+ T cells has been attracting much interest. Hitherto, both intrinsic and extrinsic mechanisms that govern CD8+ T‐cell exhaustion have been explored. Specifically, the transcriptional and epigenetic landscapes have been depicted utilizing single‐cell RNA sequencing or mass cytometry (CyTOF). In addition, cellular metabolism dictating the tumor‐infiltrating CD8+ T‐cell fate is currently under investigation. A series of clinical trials are being carried out to further establish the current strategies targeting CD8+ T‐cell exhaustion. Taken together, despite the proven benefit of immunotherapy in cancer patients, additional efforts are still needed to fully circumvent limitations of exhausted T cells in the treatment. In this review, we will focus on the current cellular and molecular understanding of metabolic changes, epigenetic remodeling, and transcriptional regulation in CD8+ T‐cell exhaustion and describe hypothetical treatment approaches based on immunotherapy aiming at reinvigorating exhausted CD8+ T cells. [ABSTRACT FROM AUTHOR]

T-cell receptor stimulation induces the convergence of multivesicular bodies towards the microtubule-organizing centre (MTOC) and the polarization of the MTOC to the immune synapse (IS). These events lead to exosome secretion at the IS. We describe here that upon IS formation centrosomal area F-actin decreased concomitantly with MTOC polarization to the IS. PKCδ-interfered T cell clones showed a sustained level of centrosomal area F-actin associated with defective MTOC polarization. We analysed the contribution of two actin cytoskeleton-regulatory proteins, FMNL1 and paxillin, to the regulation of cortical and centrosomal F-actin networks. FMNL1 β phosphorylation and F-actin reorganization at the IS were inhibited in PKCδ-interfered clones. F-actin depletion at the central region of the IS, a requirement for MTOC polarization, was associated with FMNL1 β phosphorylation at its C-terminal, autoregulatory region. Interfering all FMNL1 isoforms prevented MTOC polarization; nonetheless, FMNL1 β re-expression restored MTOC polarization in a centrosomal area F-actin reorganization-independent manner. Moreover, PKCδ-interfered clones exhibited decreased paxillin phosphorylation at the MTOC, which suggests an alternative actin cytoskeleton regulatory pathway. Our results infer that PKCδ regulates MTOC polarization and secretory traffic leading to exosome secretion in a coordinated manner by means of two distinct pathways, one involving FMNL1 β regulation and controlling F-actin reorganization at the IS, and the other, comprising paxillin phosphorylation potentially controlling centrosomal area F-actin reorganization. Ab, antibody; AICD, activation-induced cell death; AIP, average intensity projection; APC, antigen-presenting cell; BCR, B-cell receptor for antigen; C, centre of mass; cent2, centrin 2; cIS, central region of the immune synapse; CMAC, CellTracker™ Blue (7-amino-4-chloromethylcoumarin); cSMAC, central supramolecular activation cluster; CTL, cytotoxic T lymphocytes; DAG, diacylglycerol; DGKα, diacylglycerol kinase α; Dia1, Diaphanous-1; dSMAC, distal supramolecular activation cluster; ECL, enhanced chemiluminescence; ESCRT, endosomal sorting complex required for traffic; F-actin, filamentous actin; Fact-low cIS, F-actin-low region at the centre of the immune synapse; FasL, Fas ligand; FMNL1, formin-like 1; fps, frames per second; GFP, green fluorescent protein; HBSS, Hank's balanced salt solution; HRP, horseradish peroxidase; ILV, intraluminal vesicles; IS, immune synapse; MFI, mean fluorescence intensity; MHC, major histocompatibility complex; MIP, maximal intensity projection; MVB, multivesicular bodies; MTOC, microtubule-organizing centre; NS, not significant; PBL, peripheral blood lymphocytes; PKC, protein kinase C; PKCδ, protein kinase C δ isoform; PLC, phospholipase C; PMA, phorbol myristate acetate; Pol. Index, polarization index; pSMAC, peripheral supramolecular activation cluster; PSF, point spread function; ROI, region of interest; SD, standard deviation; shRNA, short hairpin RNA; SEE, Staphylococcus enterotoxin E; SMAC, supramolecular activation cluster; TCR, T-cell receptor for antigen; T-helper (Th); TRANS, transmittance; WB, Western blot. [ABSTRACT FROM AUTHOR]

Cytokine‐induced killer (CIK) cells represent an exceptional T‐cell population uniting a T cell and natural killer cell‐like phenotype in their terminally differentiated CD3+CD56+ subset, which features non‐MHC‐restricted tumor‐killing activity. CIK cells have provided encouraging results in initial clinical studies and revealed synergistic antitumor effects when combined with standard therapeutic procedures. We established the international registry on CIK cells (IRCC) to collect and evaluate clinical trials for the treatment of cancer patients in 2010. Moreover, our registry set new standards on the reporting of results from clinical trials using CIK cells. In the present update, a total of 106 clinical trials including 10,225 patients were enrolled in IRCC, of which 4,889 patients in over 30 distinct tumor entities were treated with CIK cells alone or in combination with conventional or novel therapies. Significantly improved median progression‐free survival and overall survival were shown in 27 trials, and 9 trials reported a significantly increased 5‐year survival rate. Mild adverse effects and graft‐versus‐host diseases were also observed in the studies. Recently, more efforts have been put into the improvement of antitumoral efficacy by CIK cells including the administration of immune checkpoint inhibitors and modification with chimeric antigen receptorc. The minimal toxicity and multiple improvements on their tumor‐killing activity both make CIK cells a favorable therapeutic tool in the clinical practice of cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Identification of CD8+ T lymphocyte (CTL) escape mutations that compromise the pathogenic functions of the Nef protein may be relevant for an HIV‐1 attenuation‐based vaccine. Previously, HLA‐associated mutations 102H, 105R, 108D, and 199Y were individually statistically associated with decreased Nef‐mediated HLA‐I downregulation ability in a cohort of 298 HIV‐1 subtype C infected individuals. In the present study, these mutations were introduced by site‐directed mutagenesis into different patient‐derived Nef sequence backgrounds of high similarity to the consensus C Nef sequence, and their ability to downregulate HLA‐I was measured by flow cytometry in a CEM‐derived T cell line. A substantial negative effect of 199Y on HLA‐I downregulation and Nef expression was observed, while 102H and 105R displayed negative effects on HLA‐I downregulation ability and Nef expression to a lesser extent. The total magnitude of CTL responses in individuals harboring the 199Y mutation was lower than those without the mutation, although this was not statistically significant. Overall, a modest positive relationship between Nef‐mediated HLA‐I downregulation ability and total magnitude of CTL responses was observed, suggesting that there is a higher requirement for HLA‐I downregulation with increased CTL pressure. These results highlight a region of Nef that could be targeted by vaccine‐induced CTL to reduce HLA‐I downregulation and maximize CTL efficacy. Highlights: Mutant HIV‐1 Nef clones encoding immune‐driven were constructed.Mutation 199Y had a substantial negative effect on Nef‐mediated HLA‐I down‐regulation ability, a cytotoxic T cell (CTL) evasion mechanism.Findings highlight a region of Nef that could be targeted by vaccine‐induced immune responses to reduce Nef‐mediated HLA‐I down‐regulation and maximise CTL efficacy. [ABSTRACT FROM AUTHOR]

CD279 is a cell surface protein predominantly expressed on T cells. Its ligands CD273 and CD274 are expressed on antigen‐presenting cells and tumors. CD279 has been shown to act as an important immune check point by inhibiting CD8 T cell activation, and antibodies against CD279 enhance T cell‐mediated cytotoxic function. However, whether CD279 has other functions in CD4 T cell homeostasis or in mediating T cell interactions with antigen‐presenting cells remains unclear. In the present study, we show that antibody‐mediated inhibition of CD279 reduces T cell survival in bone marrow in vivo. Unexpectedly, CD279 blockade also compromised regulatory T cell and macrophage interactions by reducing their contact time. The observation that the CD273 antagonist had little effect suggests that CD274 (the second ligand of CD279) plays a more central role in contact between conventional T cells (Tcon) and macrophages. The results of the present study suggest that both CD279 ligands contribute to the interaction length between T cells and macrophages as a mechanism of maintaining Treg homeostasis. Furthermore, CD273 and CD274 are not redundant ligands because CD274 may have unique effects on Tcon in this complex immune axis. Therefore, ligand selection for check point blockade as a tool for cancer immunotherapy has important implications with respect to anti‐tumor T cell activation and the avoidance of side effects. [ABSTRACT FROM AUTHOR]

Almost 20 years ago, CD1d tetramers were developed to track invariant natural killer T (NKT) cells based on their specificity, and to define developmental steps during which differentiation markers and functional features are progressively acquired from early NKT cell precursor to fully mature NKT cell subsets. Based on these findings, a linear developmental model was proposed and subsequently used by all studies investigating the specific role of factors that control NKT cell development. More recently, based on intracellular staining patterns of lineage‐specific transcription factors such as T‐bet, GATA‐3, promyelocytic leukemia zinc finger and RORγt, a lineage differentiation model was proposed for NKT cell development. Currently, studies on NKT cells development present lineage differentiation model data in addition to the linear maturation model. In the perspective presented here, we discuss current knowledge relating to NKT cell developmental models and particularly focus on the approaches and strategies, some of which appear nebulous, used to define NKT cell developmental stages and subsets. [ABSTRACT FROM AUTHOR]

The distribution and abundance of immune cells, particularly T‐cell subsets, play pivotal roles in cancer immunology and therapy. T cells have many subsets with specific function and current methods are limited in estimating them, thus, a method for predicting comprehensive T‐cell subsets is urgently needed in cancer immunology research. Here, Immune Cell Abundance Identifier (ImmuCellAI), a gene set signature‐based method, is introduced for precisely estimating the abundance of 24 immune cell types including 18 T‐cell subsets, from gene expression data. Performance evaluation on both the sequencing data with flow cytometry results and public expression data indicate that ImmuCellAI can estimate the abundance of immune cells with superior accuracy to other methods especially on many T‐cell subsets. Application of ImmuCellAI to immunotherapy datasets reveals that the abundance of dendritic cells, cytotoxic T, and gamma delta T cells is significantly higher both in comparisons of on‐treatment versus pre‐treatment and responders versus non‐responders. Meanwhile, an ImmuCellAI result‐based model is built for predicting the immunotherapy response with high accuracy (area under curve 0.80–0.91). These results demonstrate the powerful and unique function of ImmuCellAI in tumor immune infiltration estimation and immunotherapy response prediction. [ABSTRACT FROM AUTHOR]

Hesperetin (HES) is a dihydroflavone with the molecular formula of C16H14O6. It has been reported that Hesperetin has antioxidant and anticancer effects. Recent studies showed that it can also regulate immune responses. To assess its potential function as a vaccine adjuvant, we formulated HES with inactivated B16F10 melanoma cells and determined whether it would enhance the activation of antigen‐presenting cells by experiments in vivo and in vitro. We found that HES activated the PI3K‐Akt signalling pathway in antigen‐presenting cells (APCs), enhanced cytotoxic T lymphocyte (CTL) responses and deactivated tolerogenic T cells. We also observed that inactivated B16F10 cells in combination with HES vaccine inhibited the growth of mice tumours, resulting in improved overall survival compared to the effects of inactivated B16F10 cell vaccine. To verify that CD8+T cells play a key role in inhibiting the development of melanoma, we transferred the sorted CD8+T cells from immunized mice to B16F10 challenged models and found that the survival rate of tumour‐bearing mice was significantly prolonged. Taken together, these results suggest that hesperetin can be used as a potential adjuvant to improve tumour immune responses and antigen immunogenicity. [ABSTRACT FROM AUTHOR]

T lymphocytes utilize amoeboid migration to navigate effectively within complex microenvironments. The precise rearrangement of the actin cytoskeleton required for cellular forward propulsion is mediated by actin regulators, including the actin‐related protein 2/3 (Arp2/3) complex, a macromolecular machine that nucleates branched actin filaments at the leading edge. The consequences of modulating Arp2/3 activity on the biophysical properties of the actomyosin cortex and downstream T cell function are incompletely understood. We report that even a moderate decrease of Arp3 levels in T cells profoundly affects actin cortex integrity. Reduction in total F‐actin content leads to reduced cortical tension and disrupted lamellipodia formation. Instead, in Arp3‐knockdown cells, the motility mode is dominated by blebbing migration characterized by transient, balloon‐like protrusions at the leading edge. Although this migration mode seems to be compatible with interstitial migration in three‐dimensional environments, diminished locomotion kinetics and impaired cytotoxicity interfere with optimal T cell function. These findings define the importance of finely tuned, Arp2/3‐dependent mechanophysical membrane integrity in cytotoxic effector T lymphocyte activities. [ABSTRACT FROM AUTHOR]

Tacrolimus (TAC) acts as an inhibitor of calcineurin, which inhibits the production of interleukin‐2. In this study, we aimed to design a targeted delivery platform with poly (lactide‐co‐glycolide; PLGA) nanoparticles modified with chitosan (CS) and CD8AP17s aptamer (Apt). MOLT‐4 cells as CD8 positive and JURKAT cells as CD negative were adopted to investigate the efficacy of the proposed delivery system in vitro. The particle size and Ζ potential of the TAC‐PLGA‐CS‐Apt nanocomplex were 345 nm and 13.7 mV, respectively. Release study showed an efficient TAC release from complex in citrate buffer (pH 5.5). The 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay showed that TAC‐PLGA‐CS‐Apt nanocomplex was highly selective toward MOLT‐4 cells. Complex increased the cellular uptake of TAC in MOLT‐4 cells (target) while reducing its cytotoxicity in JURKAT cells (nontarget). Our study showed that complex nanoconjugate could efficiently deliver TAC into MOLT‐4 cells as a model of cytotoxic T cell and it could be considered as a potential candidate for TAC delivery. [ABSTRACT FROM AUTHOR]

Tissue‐resident memory T (TRM) cells are abundant in the memory T cell pool and remain resident in peripheral tissues, such as the skin, where they act as alarm sensors or cytotoxic killers. TRM cells persist long after the pathogen is eliminated and can respond rapidly upon reinfection with the same antigen. When aberrantly activated, skin‐located TRM cells have a profound role in various skin disorders, including vitiligo and melanoma. Autoreactive TRM cells are present in human lesional vitiligo skin and mouse models of vitiligo, which suggests that targeting these cells could be effective as a durable treatment strategy for vitiligo. Furthermore, emerging evidence indicates that induction of melanoma‐reactive TRM cells is needed to achieve effective protection against tumor growth. This review highlights seminal reports about skin‐resident T cells, focusing mainly on their role in the context of vitiligo and melanoma, as well as their potential as therapeutic targets in both diseases. [ABSTRACT FROM AUTHOR]

The majority of human CD8 cytotoxic T lymphocytes express αβ T‐cell receptors that recognize peptide–MHC class I complexes. Considerable attention has been devoted to TCR β repertoires, but study of TCR α chains has been limited. To gain a better understanding of the features of CDR3α and CDR3β in paired samples, we comprehensively analyzed 776 unique paired αβ TCR CDR3 regions in this study. We found that (I) the CDR3 length among paired αβ TCRs had a fairly narrow distribution due to random assortment of CDR3 length in alpha and beta chains; (II) nucleotide deletions among CDR3 regions were positively correlated with insertions in both α and β TCRs; (III) the CDR3 loops of both α and β chains contained an abundance of charged/polar residues and the CDR3 base regions contained a conserved motif; and (IV) the occurrence of Gly was CDR3 length‐ and position‐dependent in both chains, whereas the frequency of Ser at positions 106 and 107 was positively correlated with CDR3 length in TCR β. Overall, the amino acids in CDR3 loop regions were significantly different between TCR α and β, which suggests a distinct role for each chain in the recognition of antigen–MHC complexes. Here, we have provided detailed information on CDR3 in paired TCRs expressed on human CD8+ T cells and established the basis of a reference set for αβ TCR repertoires in healthy humans. [ABSTRACT FROM AUTHOR]

Human herpes virus 6B (HHV‐6B) is a widespread virus that infects most people early in infancy and establishes a chronic life‐long infection with periodic reactivation. CD4 T cells have been implicated in control of HHV‐6B, but antigenic targets and functional characteristics of the CD4 T‐cell response are poorly understood. We identified 25 naturally processed MHC‐II peptides, derived from six different HHV‐6B proteins, and showed that they were recognized by CD4 T‐cell responses in HLA‐matched donors. The peptides were identified by mass spectrometry after elution from HLA‐DR molecules isolated from HHV‐6B‐infected T cells. The peptides showed strong binding to matched HLA alleles and elicited recall T‐cell responses in vitro. T‐cell lines expanded in vitro were used for functional characterization of the response. Responding cells were mainly CD3+CD4+, produced IFN‐γ, TNF‐α, and low levels of IL‐2, alone or in combination, highlighting the presence of polyfunctional T cells in the overall response. Many of the responding cells mobilized CD107a, stored granzyme B, and mediated specific killing of peptide‐pulsed target cells. These results highlight a potential role for polyfunctional cytotoxic CD4 T cells in the long‐term control of HHV‐6B infection. [ABSTRACT FROM AUTHOR]

One successful class of cancer immunotherapies, immune checkpoint inhibitory antibodies, disrupts key pathways that regulate immune checkpoints, such as cytotoxic T lymphocyte–associated antigen‐4 (CTLA‐4). These agents unleash the potency of antigen‐experienced T cells that have already been induced as a consequence of the existing tumor. But only 20% of cancers naturally induce T cells. For most cancers, vaccines are require to induce and mobilize T effector cells (Teffs) to traffick into tumors. We evaluated the effects of anti–CTLA‐4 given in combination with an antigen‐specific dendritic cell vaccine on intratumoral Teffs in a murine pancreatic cancer model. The dendritic cell–targeted tumor antigen plus anti–CTLA‐4 significantly increased the number of vaccine‐induced CD4+ Teffs within the tumor. This increase was accompanied by a reduction in the size of the peripheral CD4+ Teff pool. We also found that IL‐3 production by activated CD4+ T cells was significantly increased with this combination. Importantly, the CD4+ Teff response was attenuated in Il3−/− mice, suggesting mediation of the effect by IL‐3. Finally, the induced T cell infiltration was associated with activation of the tumor endothelium by T cell–derived IL‐3. Our findings collectively provide a new insight into the mechanism driving Teff infiltration and vascular activation in a murine pancreatic cancer model, specifically identifying a new role for IL‐3 in the anticancer immune response. [ABSTRACT FROM AUTHOR]

The article offers information on reducing regulatory T cells in bone marrow preferentially associate with the expansion of cytotoxicT lymphocytes in low risk myelodysplastic syndromes (MDS) patients; and mentions the myelodysplastic syndromes (MDS) include clonal bone marrow (BM) disorders characterised by the emergence of dysplastic progenitors in the context of ineffective haematopoiesis, peripheral cytopenias and increased risk of acute myeloid leukaemia (AML).

B Chimeric antigen receptor T cells can induce impressive response rates in patients with refractory B cell malignancies. Adoptive transfer of tumor infiltrating lymphocytes or T cell receptor-engineered T cells are other promising treatment modalities currently in clinical development. Requirements for clinical trial design for T cell-based cancer immunotherapy significantly differ from established criteria for small-molecule or antibody-based anticancer drugs. The development of cellular cancer immunotherapies is spurred by the success of anti-CD19 chimeric antigen receptor (CAR) T cells in B cell malignancies. [Extracted from the article]

Background: Transplantation of hematopoietic stem cells (HSCs) from peripheral blood (PB) or cord blood (CB) is well established. HSCs from CB are associated with a lower risk of graft-versus-host disease (GVHD), but antigen-independent expanded CB- and PB-derived T cells can induce GVHD in allo-HSC recipients. CB-derived cells might be more suitable for adoptive immunotherapy as they have unique T-cell characteristics. Here, we describe functional differences between CB and PB T cells stimulated with different cytokine combinations involved in central T-cell activation.Study Design and Methods: Isolated CD8+ T cells from CB and PB were stimulated antigen independently with anti-CD3/CD28 stimulator beads or in an antigen-dependent manner with artificial antigen-presenting cells loaded with the HLA-A*02:01-restricted peptide of tumor-associated melanoma antigen recognized by T cells 1 (MART1). CB and PB T cells cultured in the presence of interleukin (IL)-7, IL-15, IL-12, and IL-21 were characterized for T-cell phenotype and specificity, that is, by CD107a, interferon-γ, tumor necrosis factor-α, and IL-2 expression.Results: After antigen-independent stimulation, activated CD8+ CB T cells exhibited stronger proliferation and function than those from PB. After antigenic stimulation, MART1-reactive CB T cells were naïve (CD45RA+CCR7+), cytotoxic, and highly variable in expressing homing marker CD62L. Addition of IL-21 resulted in increased T-cell proliferation, whereas supplementation with IL-12 decreased IL-21-induced expansion, but increased the functionality and cytotoxicity of CB and PB T cells.Conclusion: MART1-reactive CB T cells with a more naïve phenotype and improved properties for homing can be generated. The results contribute to better understanding the effects on GVHD and graft versus tumor. [ABSTRACT FROM AUTHOR]

Minor histocompatibility antigens (mHags) encoded by the Y-chromosome (H-Y-mHags) are known to play a pivotal role in allogeneic haematopoietic cell transplantation (HCT) involving female donors and male recipients. We present a new H-Y-mHag, YYNAFHWAI (UTY139-147), encoded by the UTY gene and presented by HLA-A*24:02. Briefly, short peptide stretches encompassing multiple putative H-Y-mHags were designed using a bioinformatics predictor of peptide-HLA binding, NetMHCpan. These peptides were used to screen for peptide-specific HLA-restricted T cell responses in peripheral blood mononuclear cells obtained post-HCT from male recipients of female donor grafts. In one of these recipients, a CD8+ T cell response was observed against a peptide stretch encoded by the UTY gene. Another bioinformatics tool, HLArestrictor, was used to identify the optimal peptide and HLA-restriction element. Using peptide/HLA tetramers, the specificity of the CD8+ T cell response was successfully validated as being HLA-A*24:02-restricted and directed against the male UTY139-147 peptide. Functional analysis of these T cells demonstrated male UTY139-147 peptide-specific cytokine secretion (IFNγ, TNFα and MIP-1β) and cytotoxic degranulation (CD107a). In contrast, no responses were seen when the T cells were stimulated with patient tumour cells alone. CD8+ T cells specific for this new H-Y-mHag were found in three of five HLA-A*24:02-positive male recipients of female donor HCT grafts available for this study. [ABSTRACT FROM AUTHOR]

Targeting CD40, a member of the tumor necrosis factor superfamily, using agonist antibodies (Abs) produces dramatic antitumor effects. Indeed, high-dose intravenous anti-CD40 Ab 'licenses' dendritic cells (DCs) that instruct activated CD8+ cytotoxic T cells to leave lymph nodes (LNs) and penetrate the mesothelioma tumor microenvironment. However, toxic side effects and the potential of an 'overwhelmed' immune response warrant an alternative approach. In this study, we show that injecting lower doses of anti-CD40 Ab directly into the tumor bed avoided toxic side effects and prolonged survival in 60% of mice, with most cured. Unexpectedly, DCs in tumors and LNs 'disappeared', CD8+ tumor-specific T-cell numbers and function were not enhanced, and T cells did not infiltrate regressing tumors. CD4+ or CD8+ depletion only marginally hindered anti-CD40 Ab efficacy implying another effector mechanism. B-cell numbers significantly increased in tumors, draining LNs and spleens during intratumoral anti-CD40 Ab treatment. CD40 targeting had no effect on splenic B-1 cells, obliterated marginal zone B cells and promoted follicular (FO) B-cell activity. Adoptive transfer of tumor antigen-experienced, CD40-activated B cells, or their immunoglobulin products, which recognized autoantigens on mesothelioma cells, protected against tumor challenge. Finally, studies using B-cell knockout mice showed that successful treatment of established tumors required the presence of B cells. Thus, these data suggest that CD40-activated FO B cells can become an important component of an effective antitumor immune response. [ABSTRACT FROM AUTHOR]