FIGURE 1.

HIV infection of PBLs increases TRAIL and TRAIL receptor expression, but TRAIL:TRAIL receptor blockade does not alter HIV-associated cell death. A and B, peripheral blood lymphocytes from HIV-negative donors were infected in vitro with HIV-1 (IIIB) or mock-infected and analyzed 4 days following infection for surface TRAIL receptor expression (A) or surface TRAIL expression (B). Mock-infected PBLs (light gray histograms), HIV-infected PBLs (dark gray histograms), or isotype (black histograms) are shown. Co-staining for the HIV antigen p24 revealed that the increase in TRAIL expression occurred within the population of PBLs also staining positive for p24 (results representative of four independent experiments). C, soluble TRAIL was measured in the culture supernatants of mock- or HIV-infected PBLs. The results shown are the means of four infections ± S.E. D, TRAIL-mediated death in PBL cultures was determined by serial treatment of PBL cultures (mock- and HIV-infected) with an isotype control antibody or neutralizing anti-TRAIL antibody. Independent experiments confirmed the ability of the neutralizing antibody (clone 2E5) to inhibit TRAIL-mediated death in TRAIL-sensitive cells treated with skTRAIL. The data are representative of three separate replicates.