Figure 2.
Effect of pretreatment with selected cytokines on induction of STAT6 activity by IL-4 in monocytes. Monocytes (4 × 106 cells per ml) were preincubated for 1 hr at 37°C with medium alone, IFN-β, IFN-γ, IL-1β, IL-2, M-CSF, GM-CSF, IL-6, or TGF-β (10 ng/ml each). At the end of this primary incubation period, IL-4 (1 ng/ml) was added (lanes 2–10), and the cultures were incubated for an additional 30 min. Nuclear protein extracts were prepared and assayed by EMSA for STAT6 activity by using radiolabeled IL-1ra SBE1 probe. In lanes 11–15, monocytes were preincubated with medium alone (lane 11) or IFN-γ at the indicated concentrations for 1 hr. At the end of this initial incubation period, IL-4 (1 ng/ml) was added, and the cultures were incubated for an additional 30 min. Nuclear extracts then were prepared and assayed for STAT6 activity.