Effect of treatment with anti-IL-10 mAb on cytokine secretion by cocultured (deactivated) monocytes restimulated with tumor cells. Cytokine release by tumor cell-stimulated control monocytes was 3359 ± 4724 pg/ml, 1082 ± 449 pg/ml, and 547 ± 459 for TNF-alpha, IL-10, and IL-12, respectively. Cytokine release by monocytes that were cocultured and restimulated with tumor cells in the presence of isotype control for anti-IL-10 mAb (medium) was 1895 ± 3790 pg/ml, 1565 ± 396 pg/ml, and 39 ± 67 pg/ml for TNF-alpha, IL-10, and IL-12, respectively. The results are expressed as a percentage of the control monocyte response after stimulation with tumor cells. The means of three independent experiments are shown, with error bars corresponding to 1 SD.