The clinical significance of CD45RAFOXP3 naïve and CD45RAFOXP3 effector/memory Treg subsets in the development of acute graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

INTRODUCTION

It has been proposed that regulatory T cells (Tregs) might be involved in the induction of transplantation tolerance after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, little is known about the role of Treg subsets in allo-HSCT outcomes, including the development of acute graft-versus-host disease (aGVHD). Herein, we assessed for the first time the association between the frequency of regulatory T cell (Treg) subsets, including CD45RAFOXP3 naïve (nTregs) and CD45RAFOXP3 effector/memory Tregs (eTregs), and aGVHD occurrence during 90 days after allo-HSCT.

METHODS

Twenty-four pairs of donors/recipients with hematologic malignancies who underwent HLA-matched allo-HSCT were enrolled. The frequencies of nTregs and eTregs were determined via four-color flow cytometry.

RESULTS

Compared with non-aGVHD patients, aGVHD patients had a lower frequency of nTregs in their donors (*P = 0.016). The reconstitution rate of nTregs was significantly slower on day +60 post-allo-HSCT in aGVHD patients than in non-aGVHD patients (*P = 0.025). Patients who received grafts with nTregs<0.19 and a median frequency of nTregs<0.13 and eTregs<0.58 on day +30 after transplantation presented a relatively high cumulative incidence of aGVHD (*P = 0.039, *P = 0.032, and *P = 0.036, respectively). Multivariate analysis revealed that a low median total number of Tregs recovered on days +30 and + 60 post-allo-HSCT was associated with an increased incidence of aGVHD [HR = 0.199, 95 % CI, 0.041-0.969; *P = 0.046 and HR = 0.092, 95 % CI, 0.011-0.765; *P = 0.026, respectively].

CONCLUSION

This study provides novel insights showing that high donor nTreg content and rapid recovery of nTregs and eTregs early on day 30 post-transplantation are closely linked to protection from aGVHD.