The role of IL-22 on thymus recovery and its function in mice following allogeneic bone marrow transplantation

Abstract

To explore the role of IL-22 on the recovery and function of thymus from graft-versus host disease (GVHD) mice after allogeneic bone marrow transplantation (allo-BMT). GVHD model was established by using of recipient male BALB/c and donor male C57BL/6 mice(6-8 W) respectively. The mice were divided into normal group, GVHD with IL-22 group (BS+IL-22) and without IL-22 group (BS+PBS). Numbers of thymus cells were detected at different time points. The ratio of T cell subsets from thymus was observed by flow cytometry. Percentages of IFN-γ-producing and IL-17-producing CD4+ T or CD8+ T cells were detected. The total number of thymus cells in BS+IL-22 mice [(14.6±5.1)×10⁴] was significantly higher than that in BS+PBS mice [(6.2±2.9)×10⁴] at 14 days after allo-BMT. Thymus cells in BS+IL-22 mice expanded continuously and reached at the level of normal mice, which were still higher than that in BS+PBS group. Although there was no impact on the ratio of mature CD4+ and CD8+ T cell from thymus, the percentage of immature CD4+CD8+ T cell increased obviously in mice treated with IL-22. Percentages of IFN-γ+CD4+ T cell [Th1:(2.42±0.75)%] and IFN-γ+CD8+ T cell [Tc1:(5.44±0.47)%] were up-regulated by IL-22 treatment, whereas no changes were detected in IL-17+CD4+ T cell (Th17) and IL-17+CD8+ T cell (Tc17). IL-22 accelerates the progress of thymus recovery, and increases the IFN-γ-producing ability of thymus CD4+ and CD8+ T cells from GVHD mice.