Intracerebroventricular injection of rats: a sensitive assay method for endogenous pyrogen circulating in rats.

OI! Abstract, Intracerebroventricular tics) injection of endogenous pyrogen (EPI into rats causes dose-related fever. To compare this procedure with the usual assay method. iv 0 injection into rabbits, a preparation ofcrude rabbit EP was titrated by both methods. The rat f icy injection procedure gave results similar in linearity and magnitude of response to the conventional rabbit iv method, but was found to be at least 50-fold more sensitive. The ic 4 assay worked fi)r human as well as rabbit EP and for partially purified as well as crude I preparations. Plasma from human or animal sources did not interfere. The rat icy and rabbit iv assay methods were also compared in their ability to detect a pyrogen in filter-sterilized --