Active caspase-8 and caspase-3 are expressed in freshly isolated blood T cells from HIV⁺ patients and are recruited following TNFR ligation.

Expression of intracellular active caspase-8 (A) and caspase-3 (B) was detected by flow cytometry in both CD4 or CD8 T lymphocytes from 10 healthy controls and 35 HIV⁺ patients including 4 patients susceptible to TNFR-mediated apoptosis (●). (C) PBMCs from a responder (R) or a nonresponder (NR) HIV-1–infected patient were incubated overnight with anti-TNFR1 or anti-TNFR2 mAbs. Detection of intracellular caspase-8 and caspase-3 on CD8 and CD4 (not shown) T cells was performed by flow cytometry. Data from a representative experiment are shown. The percentage of caspase-positive cells within CD8 T cells is indicated in each quadrant. The percentage of CD8 T cells dying of apoptosis under indicated conditions of stimulation is given for each donor.