[Effect of CD8⁺ CD28^- T Cells on Acute Graft-Versus-Host Disease after Haploidentical Hematopoietic Stem Cell Transplantation]

Objective: To investigate the effect of CD8⁺ CD28^- T cells on acute graft-versus-host disease(aGVHD) after haploidentical hematopoietic stem cell transplantation(haplo-HSCT).

Methods: The relationship between absolute count of CD8⁺ CD28^- T cells and aGVHD in 60 patients with malignant hematological diseases was retrospectively analyzed after haplo-HSCT, and the differences in the incidence rate of chronic graft-versus host disease(cGVHD), infection and prognosis between different CD8⁺ CD28^- T absolute cells count groups were compared.

Results: aGVHD occurred in 40 of 60 patients after haplo-HSCT, with an incidence rate of 66.67%. The median occurrence time of aGVHD was 32.5(20-100) days. At 30 days after the transplantation, the absolute count of CD8⁺ CD28^- T cells of aGVHD group was significantly lower than that of non-aGVHD group (P =0.03). Thus the absolute count of CD8⁺ CD28^- T cells at 30 days after transplantation can be used to predict the occurrence of aGVHD to some extent. At 30 days after transplantation, the incidence rate of aGVHD in the low cell count group (CD8⁺ CD28^- T cells absolute count < 0.06/μl) was significantly higher than that in the high cell count group (CD8⁺ CD28^- T cells absolute count ≥0.06/μl,P =0.011). Multivariate Cox regression analysis further confirmed that the absolute count of CD8⁺ CD28^-T cells at 30 days after transplantation was an independent risk factor for aGVHD, and the risk of aGVHD in the low cell count group was 2.222 times higher than that in the high cell count group (P =0.015). The incidence of cGVHD, fungal infection, EBV infection and CMV infection were not significantly different between the two groups with different CD8⁺ CD28^- T cells absolute count. The overall survival, non-recurrent mortality and relapse rates were not significantly different between different CD8⁺ CD28^- T cells absolute count groups.

Conclusion: Patients with delayed CD8⁺ CD28^- T cells reconstitution after haplo-HSCT are more likely to develop aGVHD, and the absolute count of CD8⁺ CD28^- T cells can be used to predict the incidence of aGVHD to some extent. The absolute count of CD8⁺ CD28^- T cells after haplo-HSCT was not associated with cGVHD, fungal infection, EBV infection, and CMV infection, and was also not significantly associated with the prognosis after transplantation.