Effects of neutralizing anti–IL-10 MoAb on neutrophil-derived PGE₂ production. Unstimulated or LPS-stimulated (100 ng/mL) neutrophils (1 × 10⁶ cells) were cultured for 24 hours with neutralizing anti–IL-10 MoAb 19F1 or isotype-matched control antibody (10 μg/mL) in the presence or absence of 10 ng/mL of IL-10 or IL-4. RIA for PGE₂ was performed as described in Materials and Methods. Results are expressed as the mean ± SEM of triplicate cultures. Similar results were obtained in two separate experiments. *P < .05, **P < .01 (compared with LPS only).