CD4 and HIV infectious disease: In HIV, CD107a+IFN-γ+ double-positive CD4 T cells share a transcriptional profile, including the expression of granzymes A and B and perforin, and exhibit killing activity similar to that of HIV-specific cytolytic CD8 T cells (96), suggesting that this marker combination might appropriately define CD4 CTLs, at least in the case of HIV infection.