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Severe combined immunodeficiency (SCID) is one of the most severe forms of primary immunodeficiency characterized by absence of functional T lymphocytes. It is a paediatric emergency, which is life-threatening when recognized too late. The clinical presentation varies from the classical form of SCID through atypical SCID to Omenn syndrome. In addition, there is a considerable immunological variation, which can hamper the diagnosis. In this educational review, we describe the immunopathological background, clinical presentations and diagnostic process of SCID, as well as the therapeutic possibilities. [ABSTRACT FROM AUTHOR]

It has become anticipated that regenerative medicine will extend into the field of veterinary medicine as new treatments for various disorders. Although the use of allogeneic stem cells for tissue regeneration is more attractive than that of autologous cells in emergencies, the therapeutic potential of allogeneic transplantation is often limited by allo-immune responses inducing graft rejection. Therefore, a methodology for quantifying and monitoring alloreactive T cells is necessary for evaluating allo-immune responses. The mixed lymphocyte reaction (MLR) is widely used to evaluate T cell alloreactivity. In human, flow cytometric MLR with carboxyfluorescein diacetate succinimidyl ester has been established and used as a more useful assay than conventional MLR with radioisotope labeling. However, the available information about alloreactivity based on the differences of dog major histocompatibility complex (MHC) (dog leukocyte antigen, DLA) is quite limited in dog. In this paper, we describe our established flow cytometric MLR method that can quantify the T cell alloreactivity while distinguishing cell phenotypes in dog, and T cell alloreactivity among DLA-type matched pairs was significantly lower than DLA-mismatched pairs, suggesting that our developed flow cytometric MLR method is useful for quantifying T cell alloreactivity. In addition, we demonstrated the advantage of DLA homozygous cells as a donor (stimulator) for allogeneic transplantation. We also elucidated that the frequency of alloreactive T cell precursors was almost the same as that of mouse and human (1–10%). To our knowledge, this is the first report to focus on the degree of allo-immune responses in dog based on the differences of DLA polymorphisms. [ABSTRACT FROM AUTHOR]

The aim of this paper was to look for predictors of abatacept (ABA) therapy discontinuation in patients with rheumatoid arthritis (RA). Seventy-one RA patients treated with ABA were followed up. Demographical, clinical, and laboratory parameters of the patients, including peripheral blood T and B cell populations, different rheumatoid factor and anti-cyclic citrullinated peptide autoantibodies isotypes, and serum free light chains were evaluated. Comparing patients who discontinued ABA with those still in therapy we observed: a higher proportion of smokers (51.9 vs 25.6 %; p = 0.03); a non significant lower proportion of anti-cyclic citrullinated peptide positivity (76 vs 89.5 %; p = 0.13); a lower proportion of terminally differentiated effector memory cells (TDEM) among total CD8+ T lymphocytes at baseline (22.0 % (7.8-39.2) vs 38.7 % (20.7-55.9); p = 0.002). Logistic multivariate analysis showed that only the proportion of CD8+TDEM T cells was an independent predictive factor of therapy discontinuation (OR (95 % IC) = 6.2 (1.2 to 30.8); p = 0.026). Receiver-operating characteristic analysis showed a significant performance of this biomarker for prediction of therapy discontinuation (using a cut-off of 30.6 %: AUC: 0.760 ± 0.07; p = 0.002). Patients with a low proportion of CD8+TDEM at baseline had a higher probability of discontinuing the treatment during time (log-rank test: p < 0.01). T cell characterization for identification of TDEM CD8+ T cells might be a useful test to predict discontinuation of ABA therapy. [ABSTRACT FROM AUTHOR]

Background: Intratumoural lymphocytic infiltration is strongly associated with the outcome of many human epithelial cancers. The current paper investigated whether subpopulations of tumour-infiltrating T lymphocytes are associated with certain clinicopathological parameters and the prognosis of patients with invasive bladder cancer (BCa). Patients and methods: The infiltration densities of the adaptive immune markers CD3 (the whole T cell population), FOXP3 (regulatory T cells; Tregs), CD8 (T effector cells) and CD45R0 (T effector memory cells) were analysed by immunohistochemistry and image analysis with tissue microarrays of tumour tissues from 149 patients with invasive BCa treated with radical cystectomy. The findings were correlated with certain clinicopathological parameters. Results: Higher FOXP3/CD3 [OS: p = 0.016, HR 1.29, 95 % confidence intervals (95 % CIs 1.05-1.59)] and FOXP3/CD8 (OS: p = 0.013, HR 1.32, 95 % CIs 1.06-1.65) ratios were significantly associated with briefer overall survival and time to cancer-specific death; the latter ratio represented an independent prognostic factor according to a multivariate analysis adjusted for pathological T and N stages (HR 1.32, 95 % CIs 1.05-1.67, p = 0.018). The infiltration densities of individual markers (CD3, CD8, FOXP3 and CD45R0) were not significantly associated with clinicopathological parameters or survival; however, a trend towards a better outcome was observed for higher log-transformed CD8 ( p = 0.070, HR 0.80, 95 % CIs 0.63-1.02) and CD3 ( p = 0.113, HR 0.84, 95 % CIs 0.68-1.04) infiltration values. Conclusions: A high fraction of Tregs amongst CD3- and CD8-positive lymphocytes indicated a poor prognosis, thereby emphasising the important role that Tregs play in the suppression of the anti-tumour immune response. No single lymphocytic marker was significantly correlated with clinical outcomes, but high CD3 and CD8 infiltration showed trends towards better prognosis. [ABSTRACT FROM AUTHOR]

There is a wealth of information regarding the differentiation of T-helper cells. Nevertheless, there is no general agreement on the topology and dynamical properties of the molecular network controlling the differentiation of these cells. This paper presents a continuous dynamical system to model the signaling network that controls the differentiation process of T-helper cells. The model is able to represent the differentiation from the precursor Th0 cell to any of the four effectors types (Th1, Th2, Th17, and Treg), as well as the phenotype of single null mutants. We present the first sensitivity analysis of the equations defining the Th model, showing that the qualitative dynamical behavior of the model is very robust against changes in three out of four tested parameters. The robustness of the model is in agreement with our claim that the qualitative behavior of the system is to a large extent independent of the methodological framework used for modeling. [ABSTRACT FROM AUTHOR]

The currently accepted paradigm for the primary T cell response is that effector T cells commit to autonomous developmental programs. This concept is based on several experiments that have demonstrated that the dynamics of a T cell response is largely determined shortly after antigen exposure and that T cell dynamics do not depend on the level and duration of antigen stimulation. Another experimental study has also shown that T cell responses are robust to variations in antigen-specific precursor frequency. Various mathematical models have corroborated the first result that programmed T cell responses are insensitive to the level of antigen stimulation. However, this paper proposes that programmed responses do not entirely explain the robustness of T cell dynamics to variations in precursor frequency. This work studies the hypothesis that the dynamics of a T cell response may also be governed by a feedback loop involving adaptive regulatory cells rather than by intrinsic developmental programs. We formulate two mathematical models based on T cell developmental programs. In one model, effector cells undergo a fixed number of divisions before dying. In the second model, effector cells live for a fixed time during which they may divide. The study of these models suggests that developmental programs are not sufficiently robust as they produce an immune response that directly scales with precursor frequencies. Consequently, we derive a third model based on the principle that adaptive regulatory T cells develop in the course of an immune response and suppress effector cells. Our simulations show that this feedback mechanism responds robustly over a range of at least four orders of magnitude of precursor frequencies. We conclude that the proliferation program paradigm does not entirely capture the observed robustness of T cell responses to variations in precursor frequency. We propose an alternative mechanism by which the primary T cell response is governed by an emergent group dynamic and not by individual T cell programs. [ABSTRACT FROM AUTHOR]

Innate and adaptive immune responses have many interactions that are regulated by the balance of signals initiated by a variety of activatory and inhibitory receptors. Among these, the NKG2D molecule was identified as expressed by T lymphocytes, including most CD8+ cells and a minority of CD4+ cells, designated TNK cells in this paper. Tumor cells may overexpress the stress-inducible NKG2D ligands (NKG2DLs: MICA/B, ULBPs) and the NKG2D signaling has been shown to be involved in lymphocyte-mediated anti-tumor activity. Aberrant expression of NKG2DLs by cancer cells, such as the release of soluble form of NKG2DLs, can lead to the impairment of these immune responses. Here, we discuss the significance of NKG2D in TNK-mediated anti-tumor activity. Our studies demonstrate that NKG2D+ T cells (TNK) are commonly recruited at the tumor site in melanoma patients where they may exert anti-tumor activity by engaging both TCR and NKG2D. Moreover, NKG2D and TCR triggering was also observed by peripheral blood derived T lymphocyte- or T cell clone-mediated tumor recognition, both in melanoma and colorectal cancer (CRC) patients. Notably, heterogeneous expression of NKG2DLs was found in melanoma and CRC cells, with a decrease of these molecules along with tumor progression. Therefore, through the mechanisms that govern NKG2D engagement in anti-tumor activity and the expression of NKG2DLs by tumor cells that still need to be dissected, we showed that NKG2D expressing TNK cells are a relevant T cell subtype for immunosurveillance of tumors and we propose that new immunotherapeutic interventions for cancer patients should be aimed also at enhancing NKG2DLs expression by tumor cells. [ABSTRACT FROM AUTHOR]

Antigen-specific CD4+ T cells play a critical role in protective immunity to many infectious pathogens. Although the antigen-specific CD4+ T cells can be measured by functional assays such as proliferation or cytokine enzyme-linked immunospot, such assays are limited to a specific function and cannot quantify anergic or suppressed T cells. In contrast, major histocompatiblity complex (MHC) class II tetramers can enumerate epitope-specific CD4+ T cells independent of function. In this paper, we report the construction of bovine leukocyte antigen MHC class II tetramers using a novel mammalian cell system to express soluble class II DRA/DRB3 molecules and defined immunodominant peptide epitopes of Anaplasma marginale major surface proteins (MSPs). Phycoerythrin-labeled tetramers were either loaded with exogenous peptide or constructed with the peptide epitope linked to the N terminus of the DRB3 chain. A DRB3*1101 tetramer loaded with MSP1a peptide F2-5B (ARSVLETLAGHVDALG) and DRB3*1201 tetramers loaded with MSP1a peptide F2-1-1b (GEGYATYLAQAFA) or MSP2 peptide P16-7 (NFAYFGGELGVRFAF) specifically stained antigen-specific CD4+ T cell lines and clones. Tetramers constructed with the T-cell epitope linked to the DRB3 chain were slightly better at labeling CD4+ T cells. In one cell line, the number of tetramer-positive T cells increased to approximately 94% of the CD4+ T cells after culture for 21 weeks with specific antigen. This novel technology should be useful to track the fate of antigen-specific CD4+ T-cell responses in cattle after immunization or infection with persistent pathogens, such as A. marginale, that modulate the host immune response. [ABSTRACT FROM AUTHOR]

The article presents brief information on research papers related to the field of immunology published in various science journals as of August 2005. A research paper on the trapping of membrane proteins published in a 2005 issue of the journal "Cell," describes the dynamics by which specialized CD2-rich membrane domains are formed in activated T cells. Another research paper published in a 2005 issue of "Journal of Experimental Medicine" investigates how the release and migration of mast cells to tissues is controlled.

The article discusses a study which shows that regulatory T cells (Tregs) can be used to prevent subsequent acute and chronic allograft rejection of tissues and solid transplants in a donor-specific manner in mice. In the paper, published in the journal "Nature Medicine," researchers also showed that Tregs can promote bone marrow chimerism. The researchers also presented evidence that directly alloreactive T cells has a significant role in mediating acute rejection while indirectly alloreactive T cells play a dominant role in mediating chronic rejection.

Murr1, a protein linked to copper homeostasis, is shown in a recent Nature paper to inhibit the degradation of lκBβ. This unexpected action of Murr1, which blunts both basal and stimulus-coupled activation of the NF-κB transcription factor, is key in making resting CD4 T lymphocytes nonpermissive for HIV infection. [ABSTRACT FROM AUTHOR]

The article discusses a research paper on the use of normalization of CD4 T cell metabolism for the treatment of lupus. It references the study "Normalization of CD4 T Cell Metabolism Reverses Lupus," published by Y. Yin et al., published in an issue of "Science Translational Medicine." It discusses the dependence of T-cell function on cellular metabolism, the response of polyclonal stimulation in vitro and findings on the extracellular acidification rate and oxygen consumption rate.