The identification and characteristics of IL-22-producing T cells in acute graft-versus-host disease following allogeneic bone marrow transplantation

Graft-versus-host disease (GVHD) remains the major obstacle for allogeneic bone marrow transplantation, in which many proinflammatory cytokines secreted by alloreactive donor T cells are involved. Role of IL-22 as a member of IL-10 family in GVHD is still disputed and the properties of IL-22-producing cells are unclear. We demonstrated here that CD4⁺ T cells but not CD8⁺ T cells involved in GVHD were the main cellular source of donor-derived IL-22. Th1 and Th17 cells were detected not only express classical cytokine IFN-γ or IL-17, but also contributed to IL-22 secretion in GVHD. Th22 cells characterized by the independent secretion of IL-22 were identified and occupied almost half percentage of IL-22-producing CD4⁺ T cells. The frequency of IL-22-producing CD4⁺ T cells showed dynamic changes with the development of GVHD. Finally, we observed that IL-22-producing CD4⁺ T cells in GVHD mouse carried CD62L⁻CD44^high/low surface markers. In conclusion, we illuminate the characteristics of donor-derived IL-22-producing CD4⁺ T cells, which may have potent implication for further study of pathogenesis of GVHD.