In this work, given that alloreactive CD8+ T cells are also exposed to persistent antigenic stimulation and a high antigen load, we conduct a direct comparison of phenotypic, transcriptional, and functional characteristics of PD-1+ alloreactive CD8+ T cells in mice with MHC-mismatched acute GvHD to the corresponding subsets in chronically LCMV-infected mice. The gene discussed is PDCD1; the disease is graft versus host disease.