Effect of HIV recombinant gp120 on IL-12 (p70) production by monocytes. Monocyte-enriched adherent cells were pretreated or not with HIV recombinant gp120 for 24 hours and then activated with SAC for 24 hours. Supernatants were collected and tested for IL-12 p70 secretion. Each value represents the mean ± SEM of quadruplicate culture samples.