Detection of pyrogens using human whole blood

Stimulation of human whole blood with various inflammogens to release endogenous pyrogens from leukocytes was used as an in vitro model for detection of compounds capable of inducing fever. When exposed to various concentrations of Salmonella abortus equi endotoxin lipopolysaccharide (IPS), blood incubations released several pyrogenic factors within 24 h, including interleukin 1β (IL-1β). The lower limit for quantitation of LPS was 10 picogram/ml, with IL-lβ as readout. In healthy donors, the interindividual variance of LPS-stimulated IL-1β release was ±23% (SEM n = 18). Not only endotoxin, but also further bacterial components such as muramyl dipeptide, various lipoteichoic acids, and the superantigen staphylococcus enterotoxin B induced a qualitatively similar reaction. We used blood from volunteers who had taken the antipyrogenic drug aspirin as a test for the reliability of our system: the ex vivo LPS-stimulated PGE₂ release but not the formation of IL-lβ in blood from these donors was inhibited for several hours. We propose the evaluation of this system as an in vitro method alternative to the rabbit pyrogen test.