The CD4⁺CD25^highregulatory T Cell Reconstitution after Allogenetic Stem Cell Transplantation and Its Correlations with aGVHD

Background CD4⁺CD25⁺ regulatory T cell (Treg), the most significant subset of regulatory T cells, has been found to play an important role in suppressing allogenetic immune response and controlling GVHD recently. The present single-center study monitored the ratio of CD4⁺CD25^high T cells and the expression of FOXP3 gene in peripheral blood post-transplant to assess the reconstitution of CD4⁺CD25^high Treg early after allogenetic stem cell transplantation and its correlations with aGVHD.

Methods: 22 patients undergoing allo-HSCT were enrolled. To detect the CD4⁺CD25⁺T cells and the CD4⁺CD25^high T cells subpopulations ratio in CD4⁺ T lymphocytes(CD4⁺CD25^+/CD4⁺ ACD4⁺CD25^high/CD4⁺) Athe CD4⁺CD25^high T cells subpopulations ratio in CD4⁺CD25⁺ T cells(CD4⁺CD25^high/CD4⁺ CD25⁺) Aand the expression of FOXP3 mRNA in the donor graft and periperal blood frequently after transplantation with the flow cytometry and real-time PCR assays.

Results:\|[Dagger]\|@CD4⁺CD25^high/CD4⁺ and CD4⁺CD25^high/CD4⁺CD25⁺ ratios in the donor graft were significantly lower in the aGVHD group(P<0.05)‡AEarly after transplantation, Both groups’CD4⁺CD25⁺/CD4⁺ ratio in peripheral blood increased significantly than that in the donor graft(P<0.05).CD4⁺CD25^high/CD4⁺ and CD4⁺CD25^high/CD4⁺CD25⁺ ratios were also significantly higher than that in donor graft in the aGVHD group, but not in the no-aGVHD group.‡BThe expression of FOXP3 in two groups after transplantation increased gradually, until six months after transplantation, its expression was still below the control level(P<0.05). The expression of FOXP3 was lower in the aGVHD group.

Conclusion:\|[Dagger]\|@The early activation and proliferation of the CD4⁺CD25^high regulatory T cells is critical for the maintainance of immune hemostasis and the control of aGVHD.‡AThe occurrence of aGVHD is related with lower ratios of CD4⁺CD25^high regulatory T cells in CD4⁺T cells and activated CD4⁺ effector T cells.‡BaGVHD may affect the quantities of CD4⁺CD25^high regulatory T cells and the expression of FOXP3.