Objective To explore the effect of α-galactosyleramide （α-GalCer） on immune reconstitution under acute graft-versus-host disease （aGVHD）. Methods BALB/c mice were transplanted with allogeneic C57BL/6 bone marrow cells and splenocytes （both 1 × 10^7） after receiving lethal total-body irradiation, α-GalCer （100 ug/kg） or vehicle （dimethyl- sulfoxide） was administered intraperitoneally immediately after transplantation. The effects of α-GalCer on immune reconstitufion, proliferation of T cells and B cells, hematopoiesis, and thymic microenvironment were assessed. Results The α-GalCer group exhibited higher percentages of CD3^＋, CD4^＋, CD8^＋, B220^＋, CD40＋, and CD86＋cells compared with the vehicle group. The number of colony forming unit per 1000 CD34^＋ cells in the et-GalCer group was higher than in the vehicle group （P=0.0012）. In vitro proliferation assays showed that the α-GalCer group had higher percentages of CD3^＋, CD4^＋, CD8^＋, and B220^＋ cells compared with the vehicle group. As for the results of in vivo proliferation assays, the numbers of CD3^＋, CD4^＋, CD8^＋, and B220^＋ cells were higher in the α-GalCer group than in the normal group, especially the number of B220^＋ cells （P=0.007）. Significant difference was not found in thymocyte count between the α-GalCer group and the vehicle group, nor in the percentages of CD3^＋, CD4^＋, and CD8^＋ cells. Conclusion Administration of tl-GalCer after allogeneic bone marrow transplantation may promote immune reconstitution in the presence of aGVHD.
