RESUMO
@#Human immune system(HIS)mice are usually used to evaluate the ability of tumor vaccines to induce cytotoxic T lymphocyte(CTL)effects, but they failed to accurately reflect the ability of cancer vaccines to induce humoral immune responses. In this study, human peripheral blood mononuclear cells were isolated by density gradient centrifugation and co-transplanted into NCG mice with in vitro differentiated dendritic cells(DCs)to establish a DC-HIS mouse model. In DC-HIS mice, co-transplanted antigen-presenting cells(HLA-DR+CD11c+)could colonize the spleen of model mice. Moreover, co-transplantation of DCs significantly increased the proportion of activated human CD4+ T/CD8+ T cells and B cells in HIS mice, indicating that DC-HIS mice could better mimic the human immune responses. The immunogenicity of the targeted HER2 protein vaccine(NitraTh-HER2)was evaluated using the DCs-HIS mice. The results showed that the NitraTh-HER2 vaccine was able to induce the production of HER2-specific human IgG antibodies with a significant antibody-dependent cell-mediated cytotoxicity(ADCC)effect and the lysis rate of target cell SK-BR-3 reached 47. 1%. The NitraTh-HER2 vaccine was able to produce antigen-specific CTL effect, and the lysis rate of target cell SK-BR-3 reached 14. 6%. Taken together, the DC-HIS mouse model provides an effective method for predicting the immunogenicity of human tumor vaccines.
RESUMO
The administration of autologous (recipient-derived) tolerogenic dendritic cells (ATDCs) is under clinical evaluation. However, the molecular mechanisms by which these cells prolong graft survival in a donor-specific manner is unknown. Here, we tested mouse ATDCs for their therapeutic potential in a skin transplantation model. ATDC injection in combination with anti-CD3 treatment induced the accumulation of CD8(+) CD11c(+) T cells and significantly prolonged allograft survival. TMEM176B is an intracellular protein expressed in ATDCs and initially identified in allograft tolerance. We show that Tmem176b(-/-) ATDCs completely failed to trigger both phenomena but recovered their effect when loaded with donor peptides before injection. These results strongly suggested that ATDCs require TMEM176B to cross-present antigens in a tolerogenic fashion. In agreement with this, Tmem176b(-/-) ATDCs specifically failed to cross-present male antigens or ovalbumin to CD8(+) T cells. Finally, we observed that a Tmem176b-dependent cation current controls phagosomal pH, a critical parameter in cross-presentation. Thus, ATDCs require TMEM176B to cross-present donor antigens to induce donor-specific CD8(+) CD11c(+) T cells with regulatory properties and prolong graft survival.
