High proportions of CD3+ T cells in grafts delayed lymphocyte recovery and reduced overall survival in haploidentical peripheral blood stem cell transplantation.

T cells in grafts serve an important role in the pathogenesis of graft versus host disease (GVHD) and immune recovery during HLA matched allogeneic stem cell transplantation. However, the role of T cells in the haploidentical peripheral blood stem cell transplantation (Haplo-PBSCT) is yet to be determined. In the present study, the role of CD3+ T cells in grafts and impact on hematopoietic and immune recovery, cytomegalovirus (CMV) reactivation, GVHD, relapse, progress free survival and overall survival (OS) were evaluated and analyzed. A total of 30 patients who underwent haplo-PBSCT were included in the present study. CD3+ T cells accounted for a median of 23.1% (range 8-47.4%) with a median dose of 299.7x106/kg (range 104-623.4). Patients were divided into two groups according to the CD3+ T cell count: Above the median (high T cell group) and below the median CD3+ T cell (low T cell group). No significant difference was identified between neutrophil and platelet recovery time between two groups (P>0.05). The mean lymphocyte recovery time of high T cell group and low T cell group were 107.07 days (95% CI 79.88-134.25), and 50.4 days (95% CI 41.42-59.38), respectively. The lymphocyte recovery time of high T cell group was higher that of low T cell group (P<0.05). No significant difference between CMV reactivation, chronic GVHD and primary disease relapse rates was observed between two groups (P>0.05). The cumulative incidence of grade II or above acute GVHD was higher in the high T groups compared with low T groups (P<0.05). The overall survival and progress free survival rates were higher in the low T cell group compared with the high T cell group (P<0.05). In conclusion, high levels of CD3+ T cells in the grafts were associated with delayed lymphocyte recovery and an increased risk of acute GVHD and decreased overall survival.