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Invasive aspergillosis (IA) is a leading cause of mortality in haematological patients. Appropriate activation of the innate immune system is crucial for the successful clearance of IA. Therefore, we studied the Aspergillus fumigatus-mediated activation of human granulocytes and monocyte-derived immature dendritic cells (DCs), as well as murine bone marrow-derived DCs (BMDCs) from wild type, toll-like receptor (TLR)4-deficient, TLR2 knockout, and TLR2/TLR4 double deficient mice. Aspergillus fumigatus antigens induced the activation and maturation of immature DCs as characterized by CD83 expression, upregulation of major histocompatibility complex and co-stimulatory molecules. Moreover, fungal antigens enhanced the phagocytosis and production of interleukin (IL)-8 in granulocytes. The release of IL-12 by BMDCs in response to A. fumigatus antigens was dependent on the expression of TLR2, whereas the release of IL-6 was dependent on the expression of functional TLR4 molecules. The protein precipitate of A. fumigatus supernatant provided strong stimulation of DCs and granulocytes, indicating that a factor secreted by A. fumigatus might activate innate immune cells. In conclusion, A. fumigatus antigens induced the activation of DCs and granulocytes. Our results indicated that this activation was mediated via TLR2 and TLR4. Future studies are needed to assess the clinical impact of these findings in patients at high risk for IA. [ABSTRACT FROM AUTHOR]

Multiple myeloma (MM) cells express certain tumour-associated antigens (TAAs) that could serve as targets for active-specific immunotherapy. The aim of the present study was to test the MM/dendritic cell (DC) fusion as a vaccination strategy. We fused MM cells with DC to generate fusion cells (FCs) and tested their antigen presenting cell (APC) function in mixed lymphocyte reactions and cytotoxicity assays. First, the HS Sultan and SK0-007 HAT sensitive human MM cell lines and DCs generated from peripheral blood of normal donors were fused in the presence of 50% polyethylene glycol to form FCs. Next, tumour cells freshly isolated from patients were similarly fused with autologous DCs to generate FCs. The FCs demonstrated a biphenotypic profile, confirmed both by flow-cytometry and dual immunofluorescence microscopy. These FCs induced MM-specific cytotoxicity. FCs, but not MM cells or DCs alone, were potent stimulators of autologous patient T cells. More importantly, FC-primed autologous peripheral blood mononuclear cells demonstrated major histocompatibility complex-restricted MM-specific cytolysis. These studies therefore demonstrated that MM/DC FC can trigger an autologous immune response to MM cells and formed the framework for a clinical trial currently underway. [ABSTRACT FROM AUTHOR]

Dendritic cells (DC) are potent antigen-presenting cells that can induce effective tumour-specific T-cell responses. This study investigated leucapheresis products as source of DC precursors in 48 patients undergoing autologous peripheral blood stem cell (PBSC) transplantation for haematological malignancies. Strikingly, high-dose cytarabine and etoposide plus granulocyte colony stimulating factor (G-CSF) mobilized PBSC harvests from acute myeloid leukaemia (AML) patients containing the highest number of myeloid linnegCD11cpos DC (mean: 7·04 × 106/kg, range: 1·46–19·67) which was 18·1-fold higher than in non-AML patients mobilized using chemotherapy (CT) regimens plus G-CSF. Clonality of purified linnegCD11cpos DC from CT plus G-CSF mobilized AML patients ( n = 8 ) was assessed using the human androgen-receptor locus methylation, disclosing a polyclonal pattern in five female patients. These cells displayed morphological and phenotypic features of myeloid DC precursors with expression of HLA-DR, HLA-ABC, CD86, CCR5 and CD54 molecules but lacking CD80, CD83, CD1a and CD40 antigens. Short-term culture with autologous leukaemic cell lysates plus tumour necrosis factor- α yielded maturated myeloid DC capable of triggering interleukin-2 and interferon- γ production by autologous T-lymphocytes. These findings suggest that the use of post-remission CT and G-CSF as mobilizing regimen in AML patients generates PBSC containing high doses of polyclonal myeloid linnegCD11cpos DC precursors, which could be used to design feasible immunotherapy protocols. [ABSTRACT FROM AUTHOR]

Recent studies have shown that human myeloid leukaemia cells can differentiate into dendritic cell (DC)-like cells (leukaemia-DCs) when cultured with a combination of cytokines. In the present study, we examined whether the transduction of leukaemia-DCs with OX40 ligand (OX40L), a member of the tumour necrosis factor (TNF) family, resulted in augmentation of their antigen presenting activity. Bicistronic retroviral vectors expressing both human OX40L and enhanced green fluorescent protein (EGFP) or EGFP alone were generated and used for transduction. Fresh leukaemic cells from five patients with acute myeloid leukaemia (AML) were isolated and retrovirally transduced with OX40L during the culture with a combination of cytokines from stem cell factor, fms-like tyrosine kinase (Flt)-3 ligand, granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin-4 (IL-4) and TNF- α. After 7 d, the majority of cells showed DC-like morphology, and expressed higher levels of CD80, CD86 and HLA-DR than fresh leukaemic cells. The transduction efficiency was 8·5–27·2%. Leukaemia-DCs transduced with OX40L elicited higher proliferative response of allogeneic CD4+ T cells than fresh leukaemic cells, non-transduced, or mock-transduced leukaemia-DCs. Co-culture of allogeneic CD4+ T cells with OX40L-transduced leukaemia-DCs was superior in the generation of interferon (IFN)- γ producing CD4+ T cells and in production of IFN- γ. Furthermore, OX40L-transduced leukaemia-DCs could elicit significant proliferative response of human leucocyte antigen-matched T cells from the donor in allogeneic stem cell transplantation. These results indicate that retroviral transduction of leukaemia-DCs with OX40L augments their antigen presenting cell activity and thus renders them more suitable for tumour vaccines or ex vivo stimulation of leukaemia-specific T cells. [ABSTRACT FROM AUTHOR]

Summary: Since the publication in 2017 of the revised 4th Edition of the World Health Organization (WHO) classification of haematolymphoid tumours, here referred to as WHO‐HAEM4, significant clinicopathological, immunophenotypic and molecular advances have been made in the field of lymphomas, contributing to refining the diagnostic criteria of several diseases, upgrading entities previously defined as provisional and identifying new entities. This process has resulted in two recent classification proposals of lymphoid neoplasms: the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO‐HAEM5). In this paper, we review and compare the two classifications in terms of diagnostic criteria and entity definition, focusing on T‐cell lymphomas and histiocytic/dendritic cell tumours. Moreover, we update the genetic data of the various pathological entities. The main goal is to provide a tool to facilitate the work of the pathologists, haematologists and researchers involved in the diagnosis and treatment of these haematological malignancies. [ABSTRACT FROM AUTHOR]

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is incurable with conventional therapies. Limited retrospective data have shown durable remissions after haematopoietic cell transplantation (HCT) [allogeneic (allo) or autologous (auto)]. We conducted a multicentre retrospective study in BPDCN patients treated with allo-HCT and auto-HCT at 8 centres in the United States and Canada. Primary endpoint was overall survival (OS). The population consisted of 45 consecutive patients who received an allo-HCT (n = 37) or an auto-HCT (n = 8) regardless of age, pre-transplant therapies, or remission status at transplantation. Allo-HCT recipients were younger (50 (14–74) vs. 67 (45–72) years, P = 0·01) and had 1-year and 3-year OS of 68% [95% confidence interval (CI) = 49–81%] and 58% (95% CI = 38–75%), respectively. Allo-HCT in first complete remission (CR1) yielded superior 3-year OS (versus not in CR1) [74% (95% CI = 48–89%) vs. 0, P < 0·0001]. Allo-HCT outcomes were not impacted by regimen intensity [3-year OS for myeloablative conditioning = 61% (95% CI = 28–83%) vs. reduced-intensity conditioning = 55% (95% CI = 28–76%)]. One-year OS for auto-HCT recipients was 11% (95% CI = 8–50%). These results demonstrate efficacy of allo-HCT in BPDCN, especially in patients in CR1. Pertaining to auto-HCT, our results suggest lack of efficacy against BPDCN, but this observation is limited by the small sample size. Larger prospective studies are needed to better define the role of HCT in BPDCN. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) are potent antigen-presenting cells that are uniquely capable of inducing primary immune responses. Although tumour cells may directly inhibit DC maturation, exposure to tumour products may also result in their activation. Fusions of cancer cells and DCs are being explored as cancer vaccines. The effect of tumour cell fusion on DC maturation and their functional characteristics has not been defined. In the present study, immature and mature DC generated from human CD34+ and peripheral blood precursors were fused to multiple myeloma cells in the presence of polyethylene glycol. Fusion of both immature and mature DCs with tumour cells resulted in an activated phenotype. In this regard, fusion cells expressed interleukin-12, a cytokine essential for the induction of T-helper cell type 1 immunity. In contrast to immature DCs, fusion cells also strongly expressed CC-chemokine receptor R7, which is responsible for DC migration to draining lymph nodes. Fusions generated with both immature and mature DCs also potently stimulated T-cell expression ofγ-interferon and cytotoxic T lymphocyte killing of tumour targets. These findings demonstrate that tumour cell fusion induces DC maturation and the development of an activated phenotype necessary for their effectiveness as cancer vaccines. [ABSTRACT FROM AUTHOR]

Summary: Advances in immunotherapy with T cells armed with chimeric antigen receptors (CAR‐Ts), opened up new horizons for the treatment of B‐cell lymphoid malignancies. However, the lack of appropriate targetable antigens on the malignant myeloid cell deprives patients with refractory acute myeloid leukaemia of effective CAR‐T therapies. Although non‐engineered T cells targeting multiple leukaemia‐associated antigens [i.e. leukaemia‐specific T cells (Leuk‐STs)] represent an alternative approach, the prerequisite challenge to obtain high numbers of dendritic cells (DCs) for large‐scale Leuk‐ST generation, limits their clinical implementation. We explored the feasibility of generating bivalent‐Leuk‐STs directed against Wilms tumour 1 (WT1) and preferentially expressed antigen in melanoma (PRAME) from umbilical cord blood units (UCBUs) disqualified for allogeneic haematopoietic stem cell transplantation. By repurposing non‐transplantable UCBUs and optimising culture conditions, we consistently produced at clinical scale, both cluster of differentiation (CD)34+ cell‐derived myeloid DCs and subsequently polyclonal bivalent‐Leuk‐STs. Those bivalent‐Leuk‐STs contained CD8+ and CD4+ T cell subsets predominantly of effector memory phenotype and presented high specificity and cytotoxicity against both WT1 and PRAME. In the present study, we provide a paradigm of circular economy by repurposing unusable UCBUs and a platform for future banking of Leuk‐STs, as a 'third‐party', 'off‐the‐shelf' T‐cell product for the treatment of acute leukaemias. [ABSTRACT FROM AUTHOR]

Summary: Langerhans cell histiocytosis (LCH) is a rare inflammatory myeloid neoplasia derived from immature myeloid dendritic cells with the mitogen‐activated protein kinase (MAPK) pathway gene mutation. LCH is rarely fatal, but patients develop various permanent consequences (PCs). We report the frequencies of LCH‐related PCs in paediatric patients (n = 317) treated by the JLSG‐96/02 AraC‐containing regimens. One‐third of LCH patients had at least one PC at a median follow‐up of 12 years. Central nervous system (CNS)‐related PCs (neurological and endocrinological) accounted for 21·5%, non‐CNS‐related 16·7%. We require novel therapeutic measures to further reduce the frequency of LCH‐related PCs. [ABSTRACT FROM AUTHOR]

Summary: No robust biomarkers have been yet validated to identify the recurrence of disease in classical Hodgkin Lymphoma (cHL) patients upon induction treatment. The relevance of the inflammatory microenvironment in cHL prompted us to investigate the key immunomodulator myeloid dendritic cells type‐1 (mDC1), type‐2 (mDC2) and plasmacytoid dendritic cells (pDC). Blood DC levels were assessed in 52 newly diagnosed patients through multiparametric flow‐cytometry. All but two patients received ABVD regimen (doxorubicin, bleomycin, vinblastine, dacarbazine). The median counts of all DC subsets were lower in cHL patients than in healthy controls (P < 0·001). Median mDC counts were inferior for the advanced vs early stage patients for both mDC1s and mDC2s (P = 0·008; P = 0·0007 respectively). Also, median mDC2 counts were reduced in case of bulky (P = 0·0004) and extra‐nodal (P = 0·046) disease. Patients with B symptoms had lower levels for mDC1s (P = 0·046), mDC2s (P = 0·009) and pDCs (P = 0·040). All the DC subtypes increased at the end of treatment in 26 patients (P < 0·001): 4·6‐fold for mDC1, 2·4‐fold for mDC2, 4·5‐fold for pDC and aligned DCs subsets with the reference frequencies and the interquartile ranges of the controls. In conclusion, DCs may contribute to the disturbed immunological interplay typical of cHL, prompting a further evaluation of their value as a potential new biomarker. [ABSTRACT FROM AUTHOR]

Dendritic cell sarcomas are rare tumours of antigen presenting cells. Data regarding their biology, management and outcomes are sparse. We analysed 66 patients with follicular dendritic cell sarcoma ( FDCS). Six patients also had Castleman disease, 9 had another malignancy and 13 had an autoimmune disease. Fifty-four per cent of patients presented with localized disease and 46% with systemic involvement. The median progression-free ( PFS) and overall survival ( OS) following frontline therapy was 21 and 50 months, respectively. Survival outcomes were significantly inferior in patients with extranodal, bulky or intra-abdominal disease at presentation. Stage was not associated with survival. Management approaches were heterogeneous. Patients who underwent an upfront gross total resection ( GTR) experienced better PFS and OS (both P < 0·0001). In patients who underwent a GTR, consolidative radiotherapy was associated with improved local control ( P = 0·03), PFS ( P = 0·04) and OS ( P = 0·05). In patients with measureable disease, gemcitabine with a taxane yielded an overall response rate of 80%. The pattern of relapse was predominantly locoregional. Salvage rates after recurrence were poor. Studies are underway at our institution to define the genomic profile in FDCS and identify potential novel therapeutic targets. [ABSTRACT FROM AUTHOR]

CD137 ligand ( CD137 L), a member of the tumour necrosis factor family, is expressed as a cell surface molecule. Engagement of CD137 L on haematopoietic progenitor cells induces monocytic differentiation, and in peripheral monocytes CD137 L signalling promotes differentiation to mature dendritic cells. We hypothesized that CD137 L signalling would also induce differentiation in transformed myeloid cells. Here we show that recombinant CD137 protein, which crosslinks CD137L and initiates reverse CD137 L signalling in myeloid cells, induces morphological changes (adherence, spreading), loss of progenitor markers ( CD117), expression of maturation markers ( CD11b, CD13) and secretion of cytokines that are indicative of myeloid differentiation. Under the influence of CD137 L signalling, acute myeloid leukaemia ( AML) cells acquired expression of co-stimulatory molecules ( CD80, CD86, CD40), the dendritic cell marker CD83 and dendritic cell activities, enabling them to stimulate T cells. CD137 L signalling induced differentiation in 71% (15 of 21) of AML samples, irrespective of French- American- British classification and CD137L expression level. However, the type of response varied with the AML subtype and patient sample. In summary, this study demonstrated that CD137L signalling induced differentiation in malignant cells of AML patients, and suggests that it may be worthwhile to investigate treatment with recombinant CD137 protein as a potential novel therapeutic approach for AML. [ABSTRACT FROM AUTHOR]

Interleukin 17A (IL17 A), a cytokine involved in allergy, inflammation and osteoclastogenesis, was investigated in multiple myeloma ( MM) to assess its role in the osteoclast ( OC)-like activity of marrow immature dendritic cells ( iDCs). Comparing nine MM patients with control subjects affected by monoclonal gammopathy of undetermined significance, we found high IL17A expression in the marrow plasma of MM patients in parallel with its deposits within the stromal matrix. Increased expression of the IL17A receptor ( IL17RA) was also found in primary myeloma iDCs, which underwent OC-like transdifferentiation after IL17A stimulation. To assess the role of IL17A, we measured the activity of the IL17/ IL17 RA pathway in IL17A-transdifferentiated iDCs and the expression of functional OC genes by Western blotting and real-time polymerase chain reaction. These cells showed increased RNA transcription of genes enrolled in the maturation of OCs, while NFATC1 and FOS were induced by IL17A, independently of NFKB1 phosphorylation. Moreover, the concurrent phosphorylation of the Lip isoform of CEBPB and the down-regulation of MAFB supported the activation of IL17 RA pathway in OC-like transdifferentiated iDCs that was apparently unrelated to TNFRSF11A signalling. These data emphasize the involvement of iDCs in MM hyperactive osteoclastogenesis and suggest that their bone resorption activity is also regulated, at least in vitro, by IL17RA. [ABSTRACT FROM AUTHOR]

The myelodysplastic syndromes ( MDS) are heterogeneous and can evolve into acute myeloid leukaemia ( AML). Rare familial cases are reported in which five disease genes have been identified to date ( RUNX1, CEBPA, TERC, TERT and GATA2). Here we report the genetic categorization of 27 families with familial MDS/ AML. All of these families were screened for RUNX1, CEBPA, TERC, TERT and GATA2 as well as TET2 and NPM1. Five of the 27 families had telomerase mutations; one had a RUNX1 mutation, while none were found to have TET2, CEBPA or NPM1 mutations. We identified four families with heterozygous GATA2 mutations, each associated with a different phenotype. While one of these mutations is novel, three have been previously reported: one has been described in dendritic cell, monocyte, B and NK lymphoid ( DCML) deficiency and one is in a family that has been reported in a series with primary lymphoedema with a predisposition to AML ( Emberger syndrome). In summary, genetic characterization was shown in 10 (four GATA2, three TERT, two TERC, one RUNX1) of these families; however 17 remain uncharacterized, highlighting marked genetic heterogeneity in familial MDS/ AML and the scope for further functional pathways that could give rise to this group of disorders. [ABSTRACT FROM AUTHOR]

Follicular lymphoma ( FL) comprises nearly 25% of non- Hodgkin lymphoma cases and is clinically characterized by initial sensitivity to chemotherapy followed by relapse. FL stroma contains a special type of stromal cell found in the germinal centre of lymph nodes-the follicular dendritic cell ( FDC). We first isolated tumourigenic cells from the FL cell line FLK-1 by side population ( SP) technique, and found that SP cells, which express ABCG2, were enriched by chemotherapy and radiation treatments. In vitro, SP cells were attracted by and adhered to FDCs through chemokine ( C- X- C motif) ligand 12/chemokine ( C- X- C motif) receptor 4 ( CXCL12/ CXCR4) signalling. In vivo, limiting dilution assays showed SP cells were highly enriched in cancer stem cells ( CSC), but required FDC for tumour formation in non-obese diabetic/severe combined immunodeficiency mice. Treatment with AMD3100, a specific CXCL12/ CXCR4 inhibitor, eliminated tumour growth. These findings were then verified with FL cells isolated from an FL patient's ascitic fluid ( FLA-1). Finally, we detected the ABCG2 expressing lymphoma cells in FL clinical specimens. Thus, we found that the highly tumourigenic FL cells having CSC-like activities ( FL- SC) interact with FDCs in a CXCL12/ CXCR4 dependent manner to resist chemotherapy. Our results indicate the importance of FL- SC and niche cell signalling in maintaining tumourigenicity. These signals represent novel targets for CSC eradication. [ABSTRACT FROM AUTHOR]

Vaccination with idiotype (Id) protein-pulsed dendritic cells (DCs) has been explored in multiple myeloma and the results have been disappointing. To improve the efficacy of DC vaccination in myeloma, we investigated the use of Id- and keyhole limpet haemocyanin (KLH)-pulsed, CD40 ligand-matured DCs administered intranodally. Nine patients with smouldering or stable myeloma without treatment were enrolled and DC vaccines were administered at weekly intervals for a total of four doses. Following vaccination, all patients mounted Id-specific γ-interferon T-cell response. Interleukin-4 response was elicited in two, and skin delayed-type hypersensitivity reaction occurred in seven patients. More importantly, Id-specific cytotoxic T-cell responses were also detected in five patients. Most if not all patients mounted a positive T-cell response to KLH following vaccination. At 1-year follow-up, six of the nine patients had stable disease, while three patients had slowly progressive disease even during the vaccination period. At 5-year follow-up, four of the six patients continued with stable disease. No major side effects were noted. In summary, intranodal administration of Id-pulsed CD40 ligand-matured DCs was able to induce Id-specific T and B-cell responses in patients. Current efforts are geared towards breaking tumour-mediated immune suppression and improving clinical efficacy of this immunotherapy. [ABSTRACT FROM AUTHOR]

Graft- versus-leukaemia (GvL) and graft- versus-host disease (GvHD) are both caused by alloreactive lymphocytes. We previously reported that GvHD correlated with higher numbers of effector CD4 T cells and Natural Killer cells early after allogeneic transplantation using a regimen comprising fludarabine, busulphan and alemtuzumab. Here, we assessed immune cell subset recovery in these patients in the context of early myeloid malignant disease relapse. Despite the close relationship between the GvL and GvHD immune responses, rapid recovery of lymphocyte subsets was not associated with protection from disease relapse. These results indicated that GvL may be weak in this treatment setting for patients with myelodysplastic syndromes and acute myeloid leukaemia. Consistent with low GvL activity, we previously reported that mixed T cell chimaerism had no detrimental effect on relapse in this treatment setting and instead correlated with better outcome because of reduced GvHD incidence. We now report that patients with significantly higher lymphocyte numbers prior to transplantation subsequently maintained the mixed T cell chimaeric state. This pre-transplant profile, together with absence of the early post-transplant signature indicative of GvHD predisposition, could potentially be used to identify patients suitable for early withdrawal of immunosuppression and prophylactic donor leucocyte infusion to boost GvL activity. [ABSTRACT FROM AUTHOR]

Despite novel treatment strategies, multiple myeloma (MM) remains an incurable disease with low immunogenicity and multiple immune defects. We developed an ex vivo strategy for inducing myeloma-specific cytotoxic T lymphocytes (CTLs) and demonstrate the possibility of identification and long-term in vivo monitoring of individual myeloma-specific T-cell clones using the most sensitive clonotypic assay that is able to detect low frequencies of T-cell clones (1 clonotypic cell in 106 cells). Ten patients with MM were examined for the presence of tumour-reactive T cells using dendritic cells loaded with autologous tumour cells. All patients had detectable myeloma-reactive T cells in vitro. Expanded myeloma-reactive T cells demonstrated specific cytotoxic effects against autologous tumour cells in vitro (median 39·6% at an effector:target ratio of 40:1). The clonality of myeloma-specific T cells was studied with a clonotypic assay, which demonstrated both oligoclonal and monoclonal populations of myeloma-specific T cells. CD8+ CTLs were the most immunodominant myeloma-specific T-cell clones and clinical responses were closely associated with the in vivo expansion and long-term persistence of individual CD8+ T-cell clones, usually at very low frequencies (10−3–10−6). We conclude that the clonotypic assay is the most sensitive tool for immunomonitoring of low-frequency T cells. [ABSTRACT FROM AUTHOR]

The diagnosis of plasmacytoid dendritic cell leukaemia (pDCL) is based on the immunophenotypic profile: CD4+ CD56+ lineageneg CD45RA+/ROneg CD11cneg CD116low CD123+ CD34neg CD36+ HLA-DR+. Several studies have reported pDCL cases that do not express this exact profile or expressing some lineage antigens that could thus be misdiagnosed. This study aimed to validate pDCL-specific markers for diagnosis by flow-cytometry or quantitative reverse transcription polymerase chain reaction on bone marrow samples. Expression of markers previously found in normal pDC was analysed in 16 pDCL, four pDCL presenting an atypical phenotype (apDCL) and 113 non-pDC – lymphoid or myeloid – acute leukaemia. CD123 was expressed at significantly higher levels in pDCL and apDCL. BDCA-2 was expressed on 12/16 pDCL and on 2/4 apDCL, but was never detected in the 113 non-pDC acute leukaemia cases. BDCA-4 expression was found on 13/16 pDCL, but also in 12% of non-pDC acute leukaemia. High levels of LILRA4 and TCL1A transcripts distinguished pDCL and apDCL from all other acute leukaemia (except B-cell acute lymphoblastic leukaemia for TCL1A). We thus propose a diagnosis strategy, scoring first the CD4+ CD56+/− MPOneg cCD3neg cCD79aneg CD11cneg profile and then the CD123high, BDCA-2 and BDCA-4 expression. Atypical pDCL can be also identified this way and non-pDC acute leukaemia excluded: this scoring strategy is useful for diagnosing pDCL and apDCL. [ABSTRACT FROM AUTHOR]

The t(14;18)(q32;q21) chromosomal translocation induces BCL2 protein overexpression in most follicular lymphomas. However the expression of BCL2 is not always homogeneous and may demonstrate a variable degree of heterogeneity. This study analysed BCL2 protein expression pattern in 33 cases of t(14;18)-positive follicular lymphomas using antibodies against two different epitopes (i.e. the widely used antibody BCL2/124 and an alternative antibody E17). 16/33 (49%) cases demonstrated strong BCL2 expression. In 10/33 (30%) cases, BCL2 expression was heterogeneous and in some of these, its loss appeared to be correlated with cell proliferation, as indicated by Ki67 expression. Double immunofluorescence labelling confirmed an inverse BCL2/Ki67 relationship, where in 24/28 (86%) cases cellular expression of BCL2 and Ki67 was mutually exclusive. In addition, seven BCL2 ‘pseudo-negative’ cases were identified in which immunostaining was negative with antibody BCL2/124, but positive with antibody E17. Genomic DNA sequencing of these ‘pseudo-negative’ cases demonstrated eleven mutations in four cases and nine of these were missense mutations. It can be concluded that in follicular lymphomas, despite carrying the t(14;18) translocations, BCL2 protein expression may be heterogeneous and loss of BCL2 could be related to cell proliferation. Secondly, mutations in translocated BCL2 genes appear to be common and may cause BCL2 pseudo-negative immunostaining. [ABSTRACT FROM AUTHOR]

Angioimmunoblastic T-cell lymphoma (AILT) is a malignant disease of peripheral T-cell origin that is characterized by a prominent proliferation of high endothelial venules in the lymph node. To investigate angiogenic mechanisms in AILT we measured the angiogenic mediator gene expression levels in the lymph nodes of 54 non-Hodgkin lymphoma patients, by immunostaining and quantitative reverse transcription polymerase chain reaction. Angiogenic mediators angiopoietin (Ang) 1 ( ANGPT1), Ang2 ( ANGPT2) and their receptor, Tie2 ( TEK), vascular endothelial growth factor (VEGF; VEGFA) and its receptor, VEGFR2 ( KDR), and hepatocyte growth factor ( HGF) and its receptor, c-Met ( MET) were all more highly expressed in AILT lymph nodes (16 cases) than in B-cell lymphomas (24 cases). Moreover, significantly higher Ang1 and Tie2 expression was detected in AILT cases with CD10-positive neoplastic T-cells by comparison with unspecified peripheral T-cell lymphoma (14 cases). Immunostaining confirmed the expression of Ang1 and VEGF by both neoplastic T-cells and follicular dendritic cells. These results suggest that the angiopoietin system may play an important role in the development of high vascularity in AILT lymph nodes. Consequently, as neoplastic T-cells and follicular dendritic cells are both increased in AILT and may represent an important source of angiogenic mediators, targeting these cells with anti-angiogenic strategies might represent a novel therapy for AILT. [ABSTRACT FROM AUTHOR]

Dendritic cell (DC)-based immunotherapy faces new challenges because the efficacy of DC vaccines in clinical trials has been inconsistent. Strategies to improve immune responses induced by DC are currently being explored. We have recently shown the feasibility of generating fully functional DC from acute myeloid leukaemic (AML) blasts, but with varying expression levels of the important costimulatory molecule CD86. To overcome this variability, we developed a novel bispecific diabody that simultaneously and agonistically targeted CD40 on AML-DC and CD28 on naïve T cells. Beside optimization of CD28-mediated signalling, the resulting cellular cross-linking was also hypothesized to increase the strength and duration of T cell/AML-DC interactions, thus increasing T-cell responsiveness to AML antigens. The αCD40/αCD28-bispecific diabody was found to bind to its target antigens and provoked increased T-cell–DC cluster formation. The αCD40/αCD28 diabody is capable of increasing T-cell proliferation induced by AML-DC as well as the induction of DC maturation. Importantly, priming efficacy of tumour-specific cytotoxic T cells can also be improved by cross-linking AML-DC and T cells with the αCD40/αCD28 diabody. We propose that the αCD40/αCD28-bispecific diabody can serve as a potent therapeutic tool to effectively augment anti-tumour T-cell responses elicited by AML-DC. [ABSTRACT FROM AUTHOR]

The immunomodulatory drugs (IMiDs) lenalidomide and actimid (also known as CC-4047) are thalidomide analogues which are more potent than their parental compound. In combination with rituximab, we have previously demonstrated that IMiDs have synergistic in vivo anti-tumour activity in preclinical studies in a human lymphoma severe combined immunodeficiency mouse model. This report further explored the mechanisms by which IMiDs exert their anti-lymphoma effects. Following exposure of subcutaneous lymphoma tumours in murine models to IMiDs, there was a significant increase in the recruitment of natural killer (NK) cells to tumour sites. This increase in NK cells was mediated via stimulation of dendritic cells and modification of the cytokine microenvironment associated with an increase in monocyte chemotactic protein-1, tumour necrosis factor-α and interferon-γ and probably augmented rituximab-associated antibody-dependent cellular cytotoxicity. IMiDs also had significant anti-angiogenic effects in our B-cell lymphoma models. Thus, by modulation of the immune system mediated via dendritic cells and NK cells, changing the cytokine milieu, as well as by their anti-angiogenic effects, IMiDs in combination with rituximab resulted in augmented in vivo anti-tumour effects against B-cell lymphoma. Our positive preclinical data adds additional support for the evaluation of IMiDs plus rituximab in patients with relapsed/refractory B-cell lymphoma. [ABSTRACT FROM AUTHOR]

Fifteen multiple myeloma (MM) patients who had failed maintenance therapy after tandem autologous stem cell transplantation underwent anti-idiotype (Id) vaccination with dendritic cells (DCs). CD14+-derived DCs were loaded with the autologous Id as whole protein (=6) or Id-derived class I-restricted peptides (=9) and keyhole limpet hemocyanin (KLH). Vaccination consisted of three subcutaneous (sc) and two intravenous injections of increasing DC doses at 2 weeks interval. DC therapy was well tolerated. Most patients developed both humoral and T-cell responses to KLH, suggesting immunocompetence. Eight of 15 patients developed an Id-specific T-cell proliferative response, 8/15 increased interferon-γ-secreting T cells and 4/15 showed an Id-positive delayed-type hypersensitivity test. Anti-Id cytotoxic T-lymphocyte precursors increased after DC vaccination in 2/2 evaluable patients. A more robust T-cell response was observed after sc DC injections and increased Id-specific T-cell proliferation was found up to 1 year after vaccination. VDJ-derived peptides were as effective as the whole protein in stimulating T-cell responses. Clinically, 7/15 patients have stable disease after a median follow-up of 26 months, one patient achieved durable partial remission after 40 months, and seven patients progressed. In conclusion, sc injections of cryopreserved Id-pulsed DCs were safe and, in contrast with intravenous administrations, induced anti-MM T-cell responses. [ABSTRACT FROM AUTHOR]

In chronic myeloid leukaemia (CML), dendritic cells (DC) and leukaemic cells share a common progeny, leading to constitutive expression of putative tumour antigens, such as bcr/abl, in DC. In this phase-I/II study, autologous DC were used as a vaccine in patients with chronic phase bcr/abl+ CML, who had not achieved an adequate cytogenetic response after treatment with α-interferon or imatinib. Ten patients were enrolled, DC were generated from peripheral blood monocytes and vaccination consisted of four subcutaneous injections of increasing numbers of DC (1–50 × 106 cells per injection) on days 1, 2, 8 and 21. Vaccination was feasible and safe. Improvement of the cytogenetic/molecular response, as detected by fluorescence in situ hybridization of peripheral blood mononuclear cells (PBMC), was possibly related to vaccination in four of 10 patients. In three of these patients, T cells recognizing leukaemia-associated antigens became detectable. The proliferative capacity of PBMC in response to autologous DC increased after vaccination in all evaluable patients. We conclude that vaccination with autologous, non-irradiated ‘leukaemic’ DC is feasible, safe and induces anti-leukaemic T-cell responses in some CML patients. DC vaccination might be useful in CML as postremission therapy, i.e. after treatment with tyrosine kinase inhibitors. [ABSTRACT FROM AUTHOR]

Twenty-two patients with acute myeloid leukaemia were recruited into a phase I/II clinical trial investigating the vaccination of patients in complete remission (CR) with autologous dendritic-like leukaemia cells (DLLC). At trial entry, leukaemia cells were harvested and tested for their ability to undergo cytokine-induced dendritic cell differentiation. Patients were then treated with intensive chemotherapy. Five patients achieved both CR and had leukaemia cells that successfully underwent differentiation and therefore proceeded to vaccination. Four escalating doses of DLLC were administered weekly by subcutaneous injection. Vaccination was generally well tolerated although one patient developed extensive eczema and an increased antinuclear factor titre possibly indicating induction of autoimmunity. Development of anti-leukaemic T-cell responses was assessed by enzyme-linked immunospot analysis of gamma-interferon secreting T lymphocytes and by human leucocyte antigen tetramer analysis for WT1-specific T cells. Increases in anti-leukaemic T-cell responses were demonstrated in four patients, but only two of the five remained in remission more than 12 months postvaccination. The study has demonstrated that generation of DLLC is feasible in only a subgroup of patients and is currently neither broadly applicable or clinically effective. [ABSTRACT FROM AUTHOR]

Weak immunogenicity of chronic lymphocytic leukaemia (CLL) cells may contribute to disease progression and inhibit the effectiveness of immunotherapies, such as vaccines. Agents that can enhance the antigen presenting capabilities of CLL cells might then help to improve the clinical results of immunotherapies. This study investigated the effects of the common gamma chain-binding cytokines, interleukin (IL)-2 and IL-15, on costimulatory properties of primary CLL cells from 51 patients. IL-2 improved the ability of CLL cells to stimulate T cell proliferation and increased the expression of costimulatory molecules (particularly CD80) in a dose-dependent fashion, especially in CLL cells with weak expression of CD38. CD80 and CD86 induction by IL-2 were positively regulated through the mitogen-activated protein kinase pathway, while CD86 expression was negatively regulated through Janus kinase pathways. However, further activation with protein kinase C agonists was required for IL-2 activated CLL cells to stimulate autologous T cells sufficiently to clear bystander CLL cells from mixed lymphocyte responses. IL-15 had similar effects on the costimulatory properties of CLL cells. These results suggest a role for IL-2, or IL-15, in immunotherapeutic strategies for CLL. [ABSTRACT FROM AUTHOR]

We have recently demonstrated that granulocyte colony-stimulating factor (G-CSF) stimulated the production of epithelial-cell-derived-neutrophil attractant-78 (ENA-78) by neutrophils and that ENA-78 might promote the accumulation of neutrophils that had migrated from the intravascular space into inflammatory tissues. In this study, we examined whether other chemokines could be secreted by neutrophils that had accumulated after migrating from the intravascular space into the inflammatory tissues. We demonstrated that adhesion to laminin contained in the basement membrane and Matrigel, which is an artificial basement membrane model, induced macrophage inflammatory protein-1β (MIP-1β) in neutrophils and that MIP-1β secreted by neutrophils induced the chemotaxis of dendritic cells. These findings suggest that neutrophils transmigrating through the basement membrane are stimulated to secrete MIP-1β by the basement membrane, inducing the transmigration of dendritic cells from the intravascular space into inflammatory tissues. We propose that neutrophils intervene between innate immune response and specific immune response by secreting MIP-1β during the transmigration through the basement membrane. [ABSTRACT FROM AUTHOR]

Allogeneic cord blood (CB) transplantation is associated with less severe graft- versus-host disease (GvHD), thought to be due to the immaturity of CB T cells, but how T cells interact with host and donor-derived dendritic cells (DCs) to initiate GvHD has not been elucidated. We therefore investigated the responses of CB and adult blood CD4+ T cells co-cultured with adult host DCs of different maturities. Primed by adult host DCs, CB and adult blood CD4+ T cells underwent similar changes in the expression of CD45RA/45RO, CD25, CD40L and CTLA-4. However, CB CD4+ T cells, when primed by either immature or Bacillus Calmette-Guerin mycobacteria-treated adult host DCs, produced lower interferon- γ (IFN- γ) and higher interleukin-10 (IL-10), which is a regulatory T cell-like cytokine profile, as compared with adult blood CD4+ T cells. In contrast, lipopolysaccharide (LPS)-treated adult host DCs significantly up-regulated IFN- γ and down-regulated IL-10 production levels from CB CD4+ T cells to that from adult blood CD4+ T cells. The sustained low IFN- γ and high IL-10 production from CB CD4+ T cells co-cultured with adult blood DCs might account for the less severe GvHD occurrence after CB transplantation, which could be reversed by LPS-treated adult blood DCs. [ABSTRACT FROM AUTHOR]

Several reports have described various strategies of dendritic cell (DC) vaccination to induce specific T-cell responses in patients with acute myeloid leukaemia (AML). About 50–60% of AML cases blasts have chromosomal abnormalities, such as inv(16) or t(8,21), which could encode for leukaemia-specific antigenic peptide sequences, possibly presented in the context of self-major histocompatibility complex (MHC) molecules. As the co-culture of AML blasts with T lymphocytes seldom resulted in T-cell stimulation, we fused AML blasts with autologous DC to enhance this effect. The fusion cells expressed MHC class I and II, CD40, B7-1, B7-2, CD209 and several adhesion molecules. In a mixed lymphocyte hybrid reaction, the fusion cells induced the proliferation of autologous T cells. Moreover, in the special case of fusion cells established from AML blasts with the chromosomal abnormality inv(16), the autologous T lymphocytes could be primed to induce cytotoxicity against up to 70% autologous AML blasts in a effector:target ratio of 20:1. Blocking assays demonstrated that the lysis was chiefly mediated by CD8+, CCR7− T lymphocytes, which could be further expanded in the form of effector memory CD8+ T cells by repeated co-cultures with the autologous fusion cells. [ABSTRACT FROM AUTHOR]

Myeloid and plasmacytoid dendritic cells (MDCs, PDCs) play a key role in the initiation of immune responses. In this study, we show a severe reduction of MDCs and PDCs in patients with B lineage acute lymphoblastic leukaemia (B-ALL; P = 0·01 vs. controls). DCs from patients with T lineage ALL (T-ALL) were quantitatively and functionally comparable to healthy donors, as demonstrated by secretion of interleukin (IL)-12p70 and interferon-α. In vitro, the circulating CD34+ fraction of B-ALL cases did not generate either CD1a+ MDCs or PDCs, suggesting that DC development is probably affected in B-ALL, but not in T-ALL. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) are the most potent antigen-presenting cells and are therefore an attractive option as antigen carriers in vaccination protocols. Chronic lymphocytic leukaemia (CLL) represents a potential good target for these approaches. The present study was designed to investigate the feasibility of generating in vitro fully functional DCs from peripheral blood (PB) monocytes of CLL patients at different phases of the disease. Although functional DCs could be obtained from CLL samples, in patients with active disease the expression of some co-stimulatory molecules appeared to be reduced. In contrast, DCs from CLL patients in remission showed no difference from those of normal controls. Moreover, patients with active disease produced DCs with reduced allostimulatory ability when compared with normal ones, whereas the functional capacities appeared to be restored in CLL DCs from remission patients. To more precisely assess the possible inhibitory effect of CLL cells on DC development, the influence of autologous leukaemic CD19+ cells on the generation of monocyte-derived CLL DCs in vitro was investigated. The addition of CLL neoplastic cells markedly affected monocyte-derived DC maturation. In conclusion, monocytes from CLL patients with active disease give rise to DCs, which show phenotypic and functional defects that are not observed in remission CLL patients. These results need to be taken into account in the design of DC-based immunotherapeutic approaches in CLL. [ABSTRACT FROM AUTHOR]

The poor response to immunotherapy in patients with multiple myeloma (MM) indicates that a better understanding of any defects in the immune response in these patients is required before effective therapeutic strategies can be developed. Recently we reported that high potency (CMRF44+) dendritic cells (DC) in the peripheral blood of patients with MM failed to significantly up-regulate the expression of the B7 co-stimulatory molecules, CD80 and CD86, in response to an appropriate signal from soluble trimeric human CD40 ligand. This defect was caused by transforming growth factor β1 (TGF β1) and interleukin (IL)-10, produced by malignant plasma cells, and the defect was neutralized in vitro with anti-TGF β1. As this defect could impact on immunotherapeutic strategies and may be a major cause of the failure of recent trials, it was important to identify a more clinically useful agent that could correct the defect in vivo. In this study of 59 MM patients, the relative and absolute numbers of blood DC were only significantly decreased in patients with stage III disease and CD80 up-regulation was reduced in both stage I and stage III. It was demonstrated that both IL-12 and interferon- γ neutralized the failure to stimulate CD80 up-regulation by huCD40LT in vitro. IL-12 did not cause a change in the distribution of DC subsets that were predominantly myeloid (CD11c+ and CDw123−) suggesting that there would be a predominantly T-helper cell type response. The addition of IL-12 or interferon- γ to future immunotherapy trials involving these patients should be considered. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) play an important role in innate and adaptive immunity. There are two major populations of blood DCs, myeloid DCs (myDCs) and plasmacytoid DCs (pcDCs). pcDCs are particularly important in antiviral as well as in general host defence, as they are the principal producers of type I interferons (IFNs). In this study, we analysed myDCs and pcDCs in healthy controls, human T-cell leukaemia virus type I (HTLV-I)-infected asymptomatic carriers (ACs), and patients with adult T-cell leukaemia (ATL). ATL patients had significantly decreased number of pcDCs and myDCs compared with controls. IFN- α production by peripheral blood mononuclear cells (PBMCs) was markedly reduced in ATL patients. Purified pcDCs from ACs were found to have impaired IFN- α-producing capacity, suggesting a functional defect in pcDCs in HTLV-I-infected individuals. Interestingly, pcDCs were shown to be susceptible to HTLV-I infection. Thus, impaired IFN- α production by pcDCs may contribute to the immunodeficiency observed in ATL. Furthermore, IFN- α-producing capacity was inversely correlated with HTLV-I proviral load in PBMCs from ACs, suggesting a role for pcDCs in maintaining the carrier state. Taken together, we hypothesize that the depletion and impaired IFN- α-producing capacity of blood DCs may contribute to the immunodeficiency in ATL and/or the development of ATL. [ABSTRACT FROM AUTHOR]

Summary. Cytomegalovirus (CMV) infection is a dangerous complication in immunosuppressed individuals such as allogeneic stem cell transplant patients. CMV disease can be prevented by the early post-transplant transfer of donor-derived, CMV-directed, T cells. Fast and cost efficient methods to generate CMV-specific T cells are, therefore, warranted. The current study utilized peptide-pulsed and adenovirus-transduced dendritic cells (DC) to generate CMV-restricted T cells. After one stimulation with CMV pp65495-503 peptide-pulsed DC and three re-stimulations with peptide-pulsed monocytes, virtually all T cells were CD8+ , expressed the relevant T cell receptor and exhibited high peptide-specific lytic activity. After only one stimulation, pp65495-503 -restricted T cells could be sorted to a purity of higher than 95% and expanded up to 1000-fold in 2 weeks. This technique may prove useful for the rapid generation of large quantities of specific cytolytic T lymphocytes (CTL) for cell therapy. DC transduced with an adenoviral vector encoding the full-length pp65 protein (Adpp65) were able to simultaneously expand CTL against multiple epitopes of pp65. In addition, they activated CMV-specific CD4+ T-helper cells. This approach would stimulate multiple-epitope populations of pp65-specific T cells and could be made available to patients of any human leucocyte antigen (HLA) haplotype. DC transduced with adenoviral vectors to express full-length antigens may prove to be potent vaccines against viral pathogens and cancer. [ABSTRACT FROM AUTHOR]

Summary. Chronic myeloid leukaemia (CML) dendritic cells (DC) are possible candidates for inducing antileukaemic immunity. This study aimed to investigate the frequency, phenotype and function of blood-derived leukaemic DC in comparison with DC from healthy donors using flow cytometric assays and mixed leucocyte reaction (MLR). Immature leukaemic DC displayed a reduced endocytotic capacity as compared with healthy controls. Moreover, in vitro maturation of leukaemic DC was found to be deficient. Expression of CD80, CD83, CD86, and major histocompatibility complex class I and class II antigens were reduced on lipopolysaccharide (LPS)-matured leukaemic DC but were enhanced by a mixture of interleukin 1β (IL-1β), IL-6, tumour necrosis factor-α (TNF-α) and prostaglandin E2 (PGE2 ). Upon stimulation with bacterial LPS, intracellular TNF-α and IL-8 production was diminished in maturing DC from CML patients. This distinct cytokine deficiency was overcome when leukaemic DC were stimulated with cytokines/PGE2 . MLR showed fully functional leukaemic DC after TNF-α-induced maturation, but a reduced proliferative alloresponse of leukaemic peripheral blood mononuclear cells. Further, intracellular production of cytokines in CML-derived T cells was markedly reduced. These data indicated that, in CML, the maturation response of leukaemic monocyte-derived DC to a natural stimulus like LPS is abnormal and may be caused by an aberrant TNF-α response in these cells. Thus, TNF-α alone or in combination with pro-inflammatory and T-cell stimulatory cytokines should be considered as an adjuvant for DC-based immunotherapy in CML. [ABSTRACT FROM AUTHOR]

Describes the generation and characteristics of dendritic cells (DC) from blood of chronic lymphocytic leukaemia patients with an indolent disease to elucidate using autologous DC for vaccine therapy. Analysis of the functional capability of DC; Identification of two distinct DC populations in patients as well as in controls; Presentation of tumor antigens in a therapeutic vaccination approach.

Long-term stroma-dependent cultures from murine spleen have been previously shown to support dendritic cell (DC) development in vitro. Secondary cultures have now been established using a splenic stromal cell layer overlaid with cells from different lymphoid sites. Cells resembling DCs can be generated in vitro from unfractionated murine lymphoid cells in the absence of added growth factors. Bone marrow (BM) cultures are the most successful but some cultures have been derived from spleen and thymus. Large numbers of mononuclear cells with dendritic morphology can be generated from BM within 2 weeks and cell production in many cultures has been maintained for at least 6 months. A significant proportion of cells binds antibodies specific for DC markers. No lymphoid cells, mast cells or granulocytes are detectable in culture by antibody and histochemical staining and light and electron microscopy. As with cells generated in primary cultures, cells grown in secondary cultures are equally potent stimulators of both syngeneic and allogeneic mixed lymphocyte reactions, confirming their function as antigen-presenting cells. They are also capable of endocytosing and presenting protein antigen to the D10.G4.1 Th2 clone and to unprimed T cells. This study confirmed the presence of DC precursors in multiple lymphoid sites which can be induced to proliferate in the presence of a spleen stromal cell monolayer. The secondary culture system provides an ideal in vitro model for investigation of the development of DC from different tissue sites. It also provides a stable and continuous resource of cells for further studies on DC development. [ABSTRACT FROM AUTHOR]

Despite the key role played by dendritic cells (DCs) in the physiology of immunity and related diseases, their differentiation pathway has not yet been fully elucidated. In this study we demonstrated that cells obtained from mouse peritoneal cavity lavage can be induced to differentiate in vitro along the dendritic lineage by the addition of optimal concentrations of murine recombinant GM-CSF (50 U/ml) for 6 d. At morphological analysis, GM-CSF-treated peritoneal cells appeared loosely adherent to plastic and showed cytoplasmic protrusions and veils typical of DCs. A de novo expression of the DC phenotypic markers MIDC8, DEC205, CD11c and relB with up-regulation of surface MHC-II and complete down-regulation of non-specific esterase (NSE) was also observed in peritoneal cells upon GM-CSF treatment. Functionally, GM-CSF-treated peritoneal cells were highly stimulatory in a mixed lymphocyte reaction, showed a reduced phagocytosis of latex particles and enhanced pinocytic activity. Moreover, tumour necrosis factor (TNF)-α (5–10 ng/ml) was able to synergize with GM-CSF in the induction of DC differentiation. On the other hand, when peritoneal cells were induced to differentiate into macrophages by treating in vivo the animals with thioglycollate before peritoneal harvesting, they completely lost the ability to acquire in vitro the dendritic phenotype in response to GM-CSF, either used alone or in combination with TNF-α. These results were confirmed by limiting dilution experiments which demonstrated the differentiation of peritoneal cells into DCs at the single cell level. Taken together, these data suggest that resting peritoneal cells in the mouse represent an immature population, capable of further differentiation along either the dendritic or the macrophagic pathway, depending on the type of stimuli they receive. [ABSTRACT FROM AUTHOR]

The presence of Kaposi's sarcoma associated herpesvirus (KSHV) in bone marrow dendritic cells, in bone marrow biopsies and in dendritic cells of peripheral blood from patients with multiple myeloma (MM) has been reported. These data suggested an association between infection with KSHV and the development of MM. The mobilization of infected cells into leukapheresis products (LP) has also been described. We assessed the LP of 35 patients with MM for the presence of KSHV using a sensitive and specific nested PCR assay, capable of detecting one copy of the virus genome. None of the samples tested revealed positivity for KSHV after amplification and subsequent hybridization with a KSHV-specific probe. Amplification products of approximately the same size as the positive control seen in eight samples did not hybridize with the specific oligonucleotide. No homologies of these products to the KSHV genome could be discovered after sequencing. Therefore we have no evidence that LP of patients with MM bear KSHV, and they can therefore be used as a source for dendritic cells for immunotherapy. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) are the most powerful professional antigen-presenting cells (APC), specializing in capturing antigens and stimulating T-cell-dependent immunity. In this study we report the generation and characterization of functional DCs derived from both steady-state bone marrow (BM) and circulating haemopoietic CD34+ cells from 14 individuals undergoing granulocyte colony-stimulating factor (G-CSF) treatment for peripheral blood stem cells (PBSC) mobilization and transplantation. Clonogenic assays in methylcellulose showed an increased frequency and proliferation of colony-forming unit-dendritic cells (CFU-DC) in circulating CD34+ cells, compared to that of BM CD34+ precursors in response to GM-CSF and TNF-α with or without SCF and FLT-3L. Moreover, peripheral blood (PB) CD34+ cells generated a significantly higher number of fully functional DCs, as determined by conventional mixed lymphocyte reactions (MLR), than their BM counterparts upon different culture conditions. DCs derived from mobilized stem cells were also capable of processing and presenting soluble antigens to autologous T cells for both primary and secondary immune response. Replacement of the early-acting growth factors SCF and FLT-3L with IL-4 at day 7 of culture of PB CD34+ cells enhanced both the percentage of total CD1a+ cells and CD1a+CD14- cells and the yield of DCs after 14 d of incubation. In addition, the alloreactivity of IL-4-stimulated DCs was significantly higher than those generated in the absence of IL-4. Furthermore, autologous serum collected during G-CSF treatment was more efficient than fetal calf serum (FCS) or two different serum-free media for large-scale production of DCs. Thus, our comparative studies indicate that G-CSF mobilizes CD34+ DC precursors into PB and circulating CD34+ cells represent the optimal source for the massive generation of DCs. The... [ABSTRACT FROM AUTHOR]

We examined the effects of different cytokine combinations and culture conditions on the expansion and modulation of cell surface antigens of CD34+ derived dendritic cells (DCs), the most efficient antigen-presenting cells capable of stimulating resting T cells in the primary immune response. Cells with a dendritic morphology and expressing HLA-DR, CD1a, S100 and CD83 were maximally expanded under serum-free conditions with the addition of SCF, GM-CSF, TNF-α, TGF-β and Flt-3 ligand (fold increase of CD1a+ cells = 102 ± 32 after 2 weeks of culture). CD34+ cells were also grown under continuous flow conditions in an artificial capillary system; after 14 d of culture, the expansion in the total cell number was lower than that of the static cultures (3.3 ± 2 v 18.9 ± 4) but the percentage of CD1a+/CD83+/CD80+ cells was considerably higher, whereas the CD14+ cells were significantly reduced (8.9 ± 2 v 26 ± 13). In continuous perfusion cultures, low levels of DC precursors and of LTC-IC were still present up to day 14. The DCs generated under flow conditions stimulated the mixed leucocyte reaction (MLR) more than the cells grown in static cultures. By electron microscopy, cells grown in the continuous flow system showed an increased number of large cells with numerous dendritic processes and abundant multilamellar complexes. The cells expanded under these conditions were sorted on the basis of their light-scatter properties into two fractions: one containing a predominance of CD1a+/S100+/CD83+/CD80+/CD14- ‘large cells’ with great internal complexity (mature DCs); the second including ‘small cells’ either CD33+/CD14+, CD33+/CD15+ or CD33+/CD13±/CD14-. The DCs generated and selected with this... [ABSTRACT FROM AUTHOR]

Dendritic cells (DC) are antigen-presenting cells with the potential to be a powerful adjuvant in the immunotherapy of haematological malignancy, including myeloma. Recently, human herpesvirus 8 (HHV-8) infection of dendritic cells in the long-term bone marrow stromal cultures of patients with myeloma has been reported. This finding is of great potential importance regarding oncogenesis in myeloma in addition to having significant implications for the use of DC in the immunotherapy of this disease. Therefore DC generated from mobilized blood mononuclear cells (MO-DC) and purified CD34+ cells (CD34-DC) of myeloma patients were examined for the presence of HHV-8 using a sensitive PCR technique. HHV-8 was not demonstrated in MO-DC or CD34-DC and we conclude that these cells remain a suitable vehicle for investigation in the immunotherapy of myeloma. [ABSTRACT FROM AUTHOR]

The article presents a study regarding the development of two model cell lines, referred to as FC-TxFL-1 and -2, from human transformed follicular lymphoma (TxFL) cells in context of demonstrating the effect of targeted drug therapies on the same. Topics include treatment of the cells with milatuzumab, veltuzumab and other monoclonal antibodies, and induction of apoptosis. Role of c-Jun N-terminal kinases (JNK) and NF-kappa B protein (NF-κB) signalling in apoptosis is discussed.