Finally, sorted PD-1+/+ or PD-1−/− PSGL1loCD4+ T and PSGL1hiCD4+ T cells from liver and lung GVHD target tissues were adoptively transferred into GVHD-free adoptive recipients with PD-L2+/+ or PD-L2−/− B cells. Here, PDCD1LG2 is linked to graft versus host disease.