Fas-induced proliferation and apoptosis in HIV-infected patients. T cells isolated from a group of (A) HIV-infected patients (n = 7) and (B) noninfected controls (n = 5) were activated using 1 μg/mL anti-CD3 Abs combined with anti-Fas or control Abs used at 0.25- or 1-μg/mL concentrations. Apoptosis (measured by annexin-V staining after 24 hours of activation) and proliferation (measured after 4 days of activation using CFSE staining) were compared in the different cultures.