The expression of checkpoint blockade molecules PD-1, PD-L1, CTLA-4, and foxp3+CD25+CD4+ T cells (Tregs) regulate donor T cell activation and graft-vs-host disease (GvHD) in allogeneic hematopoietic stem cell transplant (allo-HSCT). The gene discussed is CD274; the disease is graft versus host disease.