Changes in inflammatory parameters. Administration of endotoxin (n = 8; 2 ng/kg) resulted in a marked increase in tumour necrosis factor (TNF)-α (closed squares, left axis) and IL-1β (open squares, right axis). In control individuals cytokine levels remained below the detection limit (n = 8; data not shown). Cytokine release was associated with fever and an increase in C-reactive protein (CRP; endotoxin group, closed squares; control group, open circles). Data are expressed as means ± standard error of the mean. The P values in the figure refer to the difference between endotoxin and control groups as analyzed using analysis of variance with repeated measures over the complete curve.