Altered balance between Th1 and Th17 cells in circulation is an indicator for the severity of murine acute GVHD

Disbalance of Th1 and Th17 can lead to inflammatory diseases and autoimmunity. Acute graft-versus-host disease (GVHD) is now considered as a compound and dysregulated immune response. Both Th1 and Th17 have been implicated in the pathophysiology of acute GVHD. Disbalance of Th1 and Th17 may also play a critical role in mediating acute GVHD. In this study, we investigated the Th1/Th17 imbalance in peripheral blood through out the pathological process of acute GVHD, using a GVHD model of C57BL/6 (H-2(b)) donor to BALB/c (H-2(d)) recipient. We also analyzed the correlation between Th1/Th17 ratio and severity of acute GVHD, and explored the potential function of Th1/Th17 imbalance in acute GVHD. Recipients received 5×10(6) spleen cells (SP) underwent more severe acute GVHD, compared with the ones received 5×10(5) SP. Severe GVHD bearing recipients had much higher proportion of Th1 cells but lower proportion of Th17 cells, compared with mild GVHD bearing ones. The Th1/Th17 ratios in both groups underwent relative changes according to the changing proportions of Th1 and Th17 cells and showed positive correlation with clinical scores of acute GVHD. We describe the changing proportions of Th1 and Th17 cells in acute GVHD, and we find that Th1/Th17 ratio is an accurate indicator for predicting the severity of acute GVHD.