TNF-α and IL-10 protein and mRNA expressions in the ex vivo model of endotoxin tolerance. (a) Schematic representation of the endotoxin tolerance (ET) model used in the present study. (b) TNF-α and IL-10 protein concentrations and (c) mRNA expressions were assessed, respectively, by ELISA in culture supernatant or by quantitative RT-PCR in cell pellet obtained in peripheral blood mononuclear cells (PBMCs) after ET induction. Mean (± standard deviation) data from 10 independent experiments in healthy volunteers are given. Gene expression results are presented as a normalized ratio vs data obtained in unstimulated cells (fold changes vs control). 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 grey columns show LPS-primed cells (two LPS stimulations: 2 ng/ml followed by 100 ng/ml). The Wilcoxon signed rank test was used to test for statistical significance (** P < 0.005 vs LPS-unprimed cells). IFN, interferon.