CD11c participates in triggering acute graft-versus-host disease during bone marrow transplantation.

CD11c is a canonical dendritic cell (DC) marker with poorly defined functions in the immune system. Here, we found that blocking CD11c on human peripheral blood mononuclear cell-derived DCs (MoDCs) inhibited the proliferation of CD4+ T cells and the differentiation into IFN-γ-producing T helper 1 (Th1) cells, which were critical in acute graft-versus-host disease (aGVHD) pathogenesis. Using allogeneic bone marrow transplantation (allo-BMT) murine models, we consistently found that CD11c-deficient recipient mice had alleviated aGVHD symptoms for the decreased IFN-γ-expressing CD4+ Th1 cells and CD8+ T cells. Transcriptional analysis showed that CD11c participated in several immune regulation functions including maintaining antigen presentation of APCs. CD11c-deficient bone marrow-derived DCs (BMDCs) impaired the antigen presentation function in coculture assay. Mechanistically, CD11c interacted with MHCII and Hsp90 and participated in the phosphorylation of Akt and Erk1/2 in DCs after multiple inflammatory stimulations. Therefore, CD11c played crucial roles in triggering aGVHD and might serve as a potential target for the prevention and treatment of aGVHD.