Histological evaluations, flow cytometry, RNA-sequencing and RT-qPCR analysis revealed that Dara efficaciously mitigated GVHD through multiple mechanisms including inhibition of the proliferation, activation and differentiation of CD8+ cytotoxic T cells, reduced expression of cytotoxic effector molecules, pro-inflammatory cytokines, chemokines and chemoattractant receptors by T cells and promotion of immunosuppressive T cells. Here, CD8A is linked to graft versus host disease.