IL-15 inhibits spontaneous and CD95/Fas-induced apoptosis of HIV-specific CD8⁺ T cells.

(A) Representative flow cytometry showing Annexin V staining of HIV-specific CD8⁺ T cells after stimulation of PBMCs with anti-CD3 antibody ± IL-15 and anti-CD95/Fas antibody ± IL-15 for 14 hours. Histograms depict HIV-specific CD8⁺ T cells gated first for lymphocytes by forward scatter (FSC) and side scatter (SSC) and then for HIV-specific CD8⁺ T cells by tetramer and CD8 staining. (B) Pooled data showing Annexin V binding of HIV-specific CD8⁺ T cells after stimulation of PBMCs with anti-CD3 antibody ± IL-15 and anti-CD95/Fas antibody ± IL-15 for 14 hours (n = 10). Horizontal lines depict means. (C) Percentage of treatment-specific apoptosis shown for CD3- and CD95/Fas-induced apoptosis in HIV-specific CD8⁺ T cells (n = 10). For treatment-specific apoptosis calculation see “Patients, materials, and methods.” Bars depict means ± standard errors. The P values were calculated by using Student t test for paired samples.