Cytokine expression in uninfected, bystander, and HIV productively infected subpopulations of CD4⁺ T cells and PBMCs. Cells were purified as described in “Materials and methods,” infected with HIV, and immunostained for CD4, HIV p24, and either IL-2, IL-4, IL-10, or IFN-γ. Data represent mean fold increase over mock/uninfected cells from at least 3 different donors. ^*P < .05.