IL-10 inhibits the IFNγ-induced tyrosine phosphorylation of STAT1. (A) Monocytes were pretreated with 10 ng/mL of IL-10 for 60 minutes, and then treated with 0.5 ng/mL of IFNγ for 20 minutes. The upper panel represents an anti-STAT1 immunoprecipitation blotted with antiphosphotyrosine antibody. The lower panel represents the same membrane reprobed with anti-STAT1. The slower migrating band is tyrosine-phosphorylated STAT1 (STAT1P). The asterisk refers to a lower molecular weight band that is frequently observed in the immunoprecipitations and is related to STAT1 activation. (B) Monocytes were prepared as in (A), except that the indicated doses of IFNγ were used. Summary of laser densitometric scans of multiple antiphosphotyrosine immunoblots is shown. The values for percentage of inhibition were calculated, and the data are presented as the mean ± standard deviation for the indicated number of independent experiments.
