Time dependence of IL-10–mediated suppression of LPS-induced IP-10 mRNA expression. (A) TG-elicited macrophages were treated with LPS (10 ng/mL) in the absence or presence of IL-10 (25 ng/mL) for the indicated times. Total RNA was prepared and levels of IP-10 and GAPDH mRNA were analyzed by northern hybridization. (B) The levels of specific mRNA on the blot shown in (A) were quantified by phosphorimage analysis. Levels of IP-10 mRNA in each sample are normalized for the levels of GAPDH mRNA. Similar results were obtained in two separate experiments.