During chronic HIV infection, IL-10 production correlates with heightened PD-1 expression on monocytes (10) and constrains the proliferative capacity and the cytokine production (i.e., IFN-γ) of HIV-specific CD4+ T cells as deduced from the ex vivo blockade of IL-10Rα (17, 26); however, the in vivo administration of recombinant IL-10 does not impact plasma viral loads or CD4+ T cell counts (27). This evidence concerns the gene CD4 and HIV infectious disease.