Conclusion RRDP had a pyrogenic effect in this in vitro whole blood model. The method was simple and enabled a sensitive and quantitative determination of the effect of the different particles. The RRDPsamples varied in their ability to generate IL-1β. Endotoxin on the particles but also other factors contributed to the pyrogenic effect. Results All samples of RRDP induced an in vitro pyrogen effect but to a different degree. The method was sensitive and formation of IL-1β could be determined

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... samples with 10 ng RRDP/ml. The endotoxin inhibitor polymyxin B reduced the particle-evoked formation of IL-1β after stimulation with 1 µg RRDP/ml but had only marginal effects in mixtures with higher concentrations of particles (10 and 100 µg/ml).