In contrast, multiple studies have indicated that PD-1 deficiency substantially promoted expansion of GC B cells and humoral immunity in ITV (infection treatment vaccine)–immunized mice (Liu T. et al., 2015; Liu T. et al., 2018); and PD-1 elimination significantly increased long-lived plasma cells by P. berghei ANKA infection (Pan et al., 2020). Here, PDCD1 is linked to infection.