PDCD1 and graft versus host disease: In contrast recipients of PD-splenocytes, that survived long-term without GVHD, had expansions of polyfunctional CD4+T cells (CD44hiIFNγ+TNFα+IL-2+) that lacked inhibitory receptor expression, and partially exhausted CD8+ T cells (CD44hiIFNγ+TNFαlow) with up-regulated PD-1, CTLA-4, and LAG-3 (Fig 4C and 4D).