Effect of IL-10 (10 ng/ml), anti-IL-10 (25 μg/ml), and IL-12 (10 ng/ml) on CD3/CD28 induced changes in Δψm (DiOC6 and JC-1 fluorescence, A), ROI production (DHR and HE fluorescence, A), and pHi (B). PBL from 10 patients with SLE were pretreated for 16 h with IL-10 (10 ng/ml), anti-IL-10 (25 μg/ml Ab), or IL-12 (10 ng/ml), then washed and stimulated with CD3 and CD28 mAbs. The Δψm and pHi were assessed 1 h, while ROI production was determined 6 h after CD3/CD28 costimulation. Values of p reflect significant enhancement of CD3/CD28-induced ROI production and elevation of pHi following pretreatment with anti-IL-10 and IL-12.