Pyrogenic Activity of Human Native and Human Recombinant Interleukins-1ß: Stabilization with Albumin Enhances the Pyrogenic Action of Recombinant Il-1ß Delivered Into the Rabbit Brain

The pyrogenic potential of natural and recombinant human IL-1β in rabbits was found to be very similar when the substances were given intravenously. Under these conditions, stabilization of rIL-Iβ with human serum albumin (HSA) failed to affect the pyrogenic activity of recombinant IL-Iβ. When the two preparations were administered directly into the PO/AH area of the brain, recombinant IL-Iβ was less pyrogenic than its natural counterpart. This lower pyrogenicity of recombinant IL-Iβ was corrected if the injected material contained HSA, which is known to stabilize in vitro the biological activities of IL-Iβ against slow degradation. The possibility is now considered that the central and peripheral systems for IL-I inactivation are different. The existence of an intrabrain IL-I pool is suggested and its significance for neuroimmunomodulation is stressed.