Defective activation of STAT1 and STAT3 tyrosine phosphorylation in IL-10–treated PMN. PMN and autologous PBMC were incubated in the presence or absence of 100 U/mL IL-10 or IFNγ for 15 minutes before lysis. STAT1 and STAT3 were immunoprecipitated and the membranes were blotted with antiphosphotyrosine antibodies (4G10). Similar amounts of immunoprecipitated material were loaded in each lane, as judged from subsequent reblotting with appropriate antibodies. The data shown are representative of 4 independent experiments.