The αEβ7 integrin CD103 is an excellent marker for identifying in vivo activated CD4+ regulatory T (Treg) cells. CD103− naive Treg cells from donors are effective in prevention but ineffective in treatment of graft versus host disease (GVHD). It is unknown whether in vivo activated donor CD103+ Treg cells can effectively treat ongoing GVHD. We have recently reported a new chronic GVHD model, in which donor DBA/2 (H-2d) spleen cells were transferred to the irradiated BALB/c (H-2d) recipients. The recipients showed chronic GVHD-like syndrome with high-levels of serum autoantibodies, proteinuria, and hair-loss, and the disease induction required both donor CD4+ T and B cells in a cell dose dependent manner (Blood, 2006). In the current studies, we observed that the percentage of CD103+ cells among donor CD4+ T cells in the recipients without disease was up to 45% and was more than two fold higher than that of the recipients with disease. The CD103+CD4+ T cells were more than 97% FoxP3+, which was similar to natural CD25hi Treg cells, but the former expressed markedly higher levels of CCR5 as compared to the latter. The CD103+ Treg cells showed markedly stronger suppression capacity as compared to freshly isolated as well as in vitro anti-CD3-activated CD25hi natural Treg cells. When injected into ongoing chronic GVHD recipients with severe proteinuria, CD103+ Treg cells (1x106) reversed proteinuria and tissue damages in 92% (11/12) of the recipients, and the recipients survived for more than 100 days. In contrast, the in vitro activated natural Treg cells reversed disease in only 25% (2/8) of the recipients, and the freshly isolated CD25hi natural Treg cells reversed none (0/12), and the treated recipients died within 45 days, which was similar to control PBS treated recipients. Furthermore, we found that infusion of the CD103+ Treg cells significantly reduced CD138+ antibody-secreting plasma cells in spleen and reduced serum levels of autoantibodies; and that infusion of the CD103+ Treg cells also significantly reduced CD44loCD62LhiSCA-1hi post-mitotic CD4+ T memory stem cells in spleen as well as pathogenic IFN-γ+CD4+ T cells in liver and nephritogenic IFN-γ+IL-10+CD4+ T cells in kidney tissues. Our results indicate that, different from CD103− naive natural Treg cells that prevent GVHD via suppressing donor T cell activation and expansion, CD103+ Treg cells ameliorate ongoing chronic GVHD via reducing activated pathogenic T and B cells.
Disclosure: No relevant conflicts of interest to declare.