OBJECTIVETo observe the effect of donor CD4+;CD25+; regulatory T cells (TReg) on hematopoietic reconstitution, immune reconstitutuion and graft-versus-host disease (GVHD) following allogeneic hematopoietic stem cell transplantation (allo-HSCT).

METHODSThirty patients were divided into high TReg group (TReg> or =10.0 x 10(6) cells/kg, n=13) and low TReg group (TReg<10.0 x 10(6) cells/kg, n=17) according to the number of TReg in the grafts. Flow cytometry (FCM) was used to detect the TReg percentage in the grafts and recipients peripheral blood T lymphocyte subsets and TReg at different time points after allo-HSCT. The hematopoietic reconstitution, immune reconstitution, TReg reconstitution, incidence of GVHD and disease-free survival were compared between the two groups.

RESULTSThe high and low TReg groups showed similar WBC reconstitution time (+8.62-/+2.29 vs +8.88-/+2.71 days, P=0.778) and platelet reconstitution time (+12.69-/+5.74 vs +15.18-/+6.71 days, P=0.613). In high TReg group, the reconstitutions of CD4+;CD3+; and CD45RO+;CD4+; T cells on day 15 and CD3+; and CD4+;CD3+; T cells on day 30 were significantly accelerated in comparison with those of the low TReg group (with P values of 0.039, 0.024, 0.014, 0.020, respectively). TReg reconstitution 15 and 180 days following the surgery was significantly faster in high TReg group than in low TReg group (P=0.013, 0.005, respectively). The incidence of acute GVHD in high TReg group (61.54%) was obviously lower than that in low TReg group (94.12%, P=0.027). A negative correlation was found between the number of infused donor TReg and the severity of acute GVHD (rs=-0.393, P=0.032). The one-year disease-free survival rates of the high and low TReg groups were (60.40-/+16.10)% and (72.00-/+12.00)%, respectively, showing no significant difference between the two groups (P=0.818).

CONCLUSIONDonor TReg may promote immunological reconstitution and TReg reconstitution, and decrease the incidence of acute GVHD after allo-HSCT.