Effect of neutralizing anti–IL-10 and anti–IL-4 antibody on intracellular IL-12 (p40/p70) staining of human monocytes pretreated with LPS or medium. Immunofluorescence was performed with human monocytes stimulated as described for 24 hours. The binding of phycoerythrin (PE)-labeled mouse anti-human IL-12 (p40/p70) is shown (vertical; horizontal: forward scatter). Quadrants were set according to the isotype-matched controls. The percentages of cells in the corresponding quadrants are given. (Left) Stimulation; (middle) preincubation with 50 ng/mL LPS; (right) preincubation with 50 ng/mL LPS and neutralizing IL-10 antibody or neutralizing IL-4 antibody, respectively.