TRAIL receptor expression on PBMC subsets and apoptosis rate of CD4⁺ T cells from patients infected with HIV-1. The expression of the TRAIL receptors R1 to R4 on (A) CD4⁺ T cells, (D) CD4⁻ T cells, (E) monocytes, and (F) pDCs was analyzed quantitatively in (1) HIV-1 progressors (n = 13), (2) HIV-1 viremic nonprogressors (n = 10), (3) nonviremic patients infected with HIV-1 receiving cART (n = 11), and (4) healthy HIV-1–seronegative persons (n = 13) by FACS. (B) Ex vivo early apoptotic CD4⁺ T cells were determined by FACS as Annexin V⁺/7-AAD⁻ T cells in HIV-1 progressors (n = 7), HIV-1 nonprogressors (n = 5), and HIV-1–seronegative healthy controls (n = 5). (C) Isolated CD4⁺ T cells were stimulated with AT-2 HIV-1 or microvesicle controls for 12 hours and subsequently analyzed for TRAIL receptor expression by FACS stainings in 2 independent experiments. (A-F) Data are given as mean percentages of positive cells minus isotype controls ± SEM.