IL-10 antagonizes the effects of IFN-γ on production of TNF-α and TNF-RII in monocytes. Monocytes (5 × 10⁶ cells/mL) were cultured overnight (18 hours) in medium alone (control) or in medium containing rhIFN-γ (10 ng/mL), rhIL-10 (10 ng/mL), or both, and then were stimulated or not with LPS (10 ng/mL) for 6 hours. At the end of the incubation period, supernatants were harvested and RNA extracts were prepared. (A) Levels of TNF-α and TNF-RII mRNA determined by Northern blot analysis. (B) Levels of TNF-α and sTNF-RII protein released by LPS-stimulated cells measured by ELISA. Values represent the mean ± SEM for triplicate determinations. Similar results were obtained in 2 separate experiments.