The suppressive action of IL-10 is stimulus-dependent. TG-elicited macrophages were treated with IFNγ (50 U/mL; A) or IFNβ (500 U/mL; B) in the absence or presence of IL-10 (25 ng/mL) for the indicated times. Total RNA was prepared and IP-10 and GAPDH mRNA were analyzed using northern hybridization. Levels of expression in each lane were quantified using phosphorimage analysis. The data presented for IP-10 mRNA are normalized to the level of GAPDH in each sample. Similar results were obtained in two separate experiments.