T lymphocytes from HIV-infected individuals are susceptible to TNFR1-and TNFR2-mediated apoptosis.

(A) Freshly isolated PBMCs from healthy subjects (n = 15) or HIV-infected donors (n = 42) were incubated overnight with coated anti-TNFR1 or anti-TNFR2 mAbs as described in “Materials and methods.” Phenotypic identification of apoptotic cells was performed by costaining of cultured cells with CD4- or CD8-specific mAbs and 7-AAD. Representative dot plots of CD4 and CD8 T cells from a control donor and an HIV-1⁺ patient are shown. Numbers in each quadrant indicate the percentage of apoptotic cells (7-AAD⁺) within CD4 and CD8 subsets under indicated culture conditions. Median percentages (25-75th percentiles) of apoptotic cells within CD4 (B) and CD8 (C) subsets are shown in both groups of donors. Statistical significance was assessed by the Wilcoxon signed rank test for paired data. (D) Cells (1 × 10⁶) submitted to indicated stimuli were fixed with 2.5% glutaraldehyde in Sorensen buffer (phosphate 0.1 M, pH = 7.4) and further dehydrated in a series of ethanol solutions (30%-100%). They were then embedded in epoxy. Sections were performed with a Reichter-Jung ultramicrotome before examination. Original magnification, × 5000 with a Jeol JEM 1200 EX electron microscope.