Effect of recombinant IFN-γ on TNF-α and IL-10 protein expressions. (a) TNF-α and (b) IL-10 protein concentrations were assessed by ELISA in culture supernatants obtained after endotoxin tolerance (ET) induction in peripheral blood mononuclear cells (PBMCs) from 10 healthy individuals. Mean (± standard deviation) data are given. Black columns represent controls (cells without any lipopolysaccharide (LPS) stimulation), white columns indicate LPS-unprimed cells (only stimulated once with 100 ng/ml LPS) and dark gray columns show LPS-primed cells (two LPS stimulations: 2 ng/ml followed by 100 ng/ml) and light grey show LPS-primed cells incubated with rIFN-γ1b (100 ng/ml). The Wilcoxon signed rank test was used to test for statistical significance († P < 0.005 vs LPS-unprimed cells; * P < 0.05 vs vehicle). IFN, interferon.