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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]