Anti-CD1C monoclonal antibody, clone FQS0749

Objective. To investigate whether the potential of abatacept to inhibit vigorous CD1c myeloid dendritic cell (MDC)-driven activation of naive and memory CD4 T cells is abrogated in the presence of T cell-activating cytokines. Methods. CD4 T cell subsets (naive [Tn], central memory [Tcm], and effector memory [Tem] T cells) were isolated from the peripheral blood (PB) of healthy controls and the PB and synovial fluid (SF) of rheumatoid arthritis (RA) patients. CD4 T cells were cocultured with autologous, thymic stromal lymphopoietin (TSLP)-primed CD1c MDCs in the presence or absence of abatacept (CTLA-4Ig) and/or interleukin-7 (IL-7) or IL-15. Subsequently, T cell proliferation and cytokine production were measured. Results. The percentages of each CD4 T cell subset from the circulation of healthy controls and RA patients were comparable and mainly consisted of Tn and Tcm cells, whereas the SF of RA patients mainly consisted of Tcm and Tem cells. Activation of CD4 T cell subsets by TSLP-primed MDCs from the RA PB was completely blocked by abatacept. Addition of IL-7 or IL-15 to the cocultures strongly increased CD4 T cell activation and overruled the inhibitory capacity of abatacept. IL-7-induced reversal was associated with robust induction of interferon-gamma, tumor necrosis factor alpha, and IL-17 secretion. Similarly, CD4 T cell proliferation induced by TSLP-primed MDCs from the SF of RA patients was strongly blocked by abatacept, but this inhibitory effect was vigorously overruled in the presence of IL-7. Conclusion. These findings indicate that the presence of T cell-activating cytokines such as IL-7 or IL-15 in the joints of RA patients reduces the capacity of abatacept to inhibit MDC-driven CD4 T cell activation. This mechanism may be one explanation for the partial, and sometimes absent, response to abatacept therapy in a subset of patients.

Advanced non-small cell lung cancer (NSCLC) leads to a high death rate in patients and is a major threat to human health. NSCLC induces an immune suppressive microenvironment and escapes from immune surveillance in vivo. At present, the molecular mechanisms of NSCLC immunopathogenesis and the immune suppressive microenvironment induced by NSCLC have not been fully elucidated. Here, we focus on the effect of NSCLC cells on the development and differentiation of human CD1c(+) conventional dendritic cell (DC) subsets mediated by CD205 and CD103. The peripheral blood mononuclear cells (PBMCs) were isolated from NSCLC patients and healthy donors. DCs were induced and cocultured with primary NSCLC cells or tumor cell line H1299. DCs without incubation with tumor cells are control. The protein expression of costimulatory molecules such as CD80 and CD86, HLA-DR, pro-/anti-inflammatory cytokines such as IL-10 and IL-12, and CD205 and CD103 on CD1c(+) DCs was detected by flow cytometry. Our data revealed two new subpopulations of human CD1c(+) DCs (CD1c(+)CD205(+)CD103(+) and CD1c(+)CD205(+)CD103(-) DC) in healthy donors and NSCLC patients. NSCLC cells modulate the development of the CD1c(+)CD205(+)CD103(+) DC and CD1c(+)CD205(+)CD103(-) DC subpopulations in vitro and ex vivo. NSCLC cells also suppress the expression of signal molecules such as CD40, CD80, CD86, and HLA-DR on CD1c(+) DCs. In addition, the production of pro-inflammatory cytokines, including IL-12 and IL-23, is downregulated by NSCLC cells; however, the secretion of anti-inflammatory cytokines, such as IL-10 and IL-27, by CD1c(+) DCs is upregulated by NSCLC cells. Our results suggest that NSCLC cells may induce immune tolerogenic DCs, which block DC-mediated anti-tumor immunity in NSCLC patients. Our data may be helpful in revealing new cellular mechanisms related to the induction of tolerogenic CD1c(+) DCs by NSCLCs and the development of an immune suppressive microenvironment that causes tumor cells to escape immune surveillance. Our results indicate a potential role for CD1c(+) DC subsets mediated by CD205 and CD103 in DC-mediated immunotherapy to target NSCLC in the future.