Taken together, these results suggest that the characteristics of PD-1+ CD8+ T cells were quite similar between acute GvHD and chronic LCMV infection, and the generation of the TCF1+PD-1+ CD8+ T cell subset is a general adaptation of CD8+ T cell differentiation in a microenvironment with persistent antigenic stimulation. The gene discussed is CD8A; the disease is graft versus host disease.