Correlation of the CD4+CD25high T-regulatory cells in recipients and their corresponding donors to acute GVHD.

Graft-versus-host disease continues to be a major life-threatening complication after allogeneic hematopoietic stem cells transplantation (aHSCT). The relationship of acute GVHD (aGVHD) with the levels of peripheral CD4(+)CD25(high) T cells in patients after aHSCT and in their corresponding donors is not fully investigated. We examined the levels of CD4(+)CD25(high) T cells in patients after aHSCT and in their corresponding donors, and analyzed the relationship of CD4(+)CD25(high) T cells to the incidence and prognosis of aGVHD. The recipients with normal or high CD4(+)CD25(high) T cells (three of eight, 37.5%) had no or mild aGVHD (grade I), and all survived during the follow-up period. In striking contrast, the recipients with lower or no CD4(+)CD25(high) T cells suffered from greater than grade II aGVHD (four of four, 100%), and all died within 1-year post-aHSCT. Moreover, the number of CD4(+)CD25(high) T cells in recipients correlated significantly with that of their corresponding donors. The CD4(+)CD25(high) T cells from the recipients and their corresponding donors expressed high levels of Foxp3, and effectively suppressed the proliferation of CD4(+)CD25(-) responder T cells. This study suggests that human Treg cells may play an important role in aGVHD, as has been seen in murine models. The levels of peripheral CD4(+)CD25(high) T cells in recipients and donors could be helpful for predicting of the onset and outcome of aGVHD.