Effect of infectious HIV-1 on sTRAIL production in tonsil culture. Ex vivo human lymphoid tissues were cultured for 12 days in absence ( and thin line) or presence of HIV-1_LAV (bold line and □). Soluble TRAIL was measured at days 3, 6, 9, and 12 by ELISA. Culture medium was changed at 3-day intervals. The statistically different (P < .05) samples from control are indicated by an asterisk. Error bars indicate standard deviation derived from 3 different ELISAs for each condition tested.