PDCD1 and malaria: In addition to examining expression of the Tr1 cell-associated coinhibitory and chemokine receptors identified above in humans infected with P. falciparum, antibodies against PD1 and TIGIT were also included in our flow cytometry panels due to their past associations with Tr1 cells in the context of intestinal inflammation (27) and the known immunomodulatory role for PD1 in malaria (37–39).