IL-12 p40 and p70 production in whole blood cultures of HIV-infected individuals in response to LPS is normal but, in response to SAC, is decreased. Whole blood (diluted 1:10) from HIV-infected individuals (closed symbols; n = 58) and noninfected controls (open symbols, n = 36) was cultured in the presence of various concentrations SAC (A,C, and E) or LPS (B,D, and F ). After 20 hours of culture, supernatants were harvested, and IL-12 p40 (A and B), IL-12 p70 (C and D), and IL-6 (E and F ) concentrations were measured in ELISA. Mean cytokine production is shown; bars indicate the standard error of the mean. IL-12 p40 and IL-12 p70 production in HIV-infected individuals differed significantly from that in noninfected controls at 0.002% SAC (P = .03), 0.008% SAC (P < .005), and 0.032% SAC (P < .005) and at 0.002% SAC (P < .005), 0.008% SAC (P < .005), and 0.032% SAC (P < .005), respectively, as determined in the Mann-Whitney U-test.