In vitro model of tolerization. PMN from healthy donors were first cultured over 24 hours in the presence or absence of eitherE coli LPS (100 ng/mL) or recombinant human IL-10 (10 ng/mL) or both. Supernatants were obtained and IL-8 was measured (A). Fresh medium was added to the cells and the PMN were further cultured for an additional 24-hour period (24-48 h) in the presence or absence of E coli LPS (1 μg/mL). IL-8 was measured in the supernatants (B). The results are the mean of eight different experiments. (b va: P = .01; c v a: P = .02; d va: P = .01; d v b: P = .01.)