Upregulation of the PD-Ls on activated CD4+ T cells in our series is consistent with the results of Mazerolles et al., who reported that PD-L1 expression on activated CD4 effector T cells is correlated with T-cell proliferation (25), and Trinchieri who observed that immunosuppressive mechanisms typical of the tumor microenvironment are observed in infected tissues during resolution of the immune response to infections (26). The gene discussed is CD4; the disease is infection.