AJP - Endocrinology and Metabolism, Vol 263, Issue 6 E1092-E1098, Copyright © 1992 by American Physiological Society
Development and application of a radioimmunoassay to detect interleukin-1 in rat peripheral circulation
R. Derijk and F. Berkenbosch
Department of Pharmacology, Medical Faculty, Free University, Amsterdam, The Netherlands.
We describe the development and application of a radioimmunoassay to detect
circulating interleukin (IL)-1 beta concentrations in the rat. No IL-1
immunoreactivity above the detection limit of the assay (100 pg/ml) could
be detected in plasma of control rats. In contrast, immunoreactive IL-1 was
detected after intravenous administration of rat recombinant IL-1 beta
(rrIL-1 beta) or bacterial lipopolysaccharide (LPS) to rats. The effect of
LPS on plasma immunoreactive IL-1 concentrations was time and dose
dependent. The immunoreactive IL-1 response to LPS was prevented by in vivo
macrophage depletion induced by liposome-directed macrophage suicide
technique. Gel filtration of plasma from LPS-treated rats revealed the
presence of a high and a smaller molecular form of immunoreactive IL-1. The
small molecular immunoreactive IL-1 peak coeluted with rrIL-1 beta and
probably represents the 17-kDa form of IL-1 beta. In conclusion, our data
support the hypothesis that IL-1 secreted by macrophages can act as a
humoral signal molecule to induce the immunological, metabolic, and
neuroendocrine changes in response to bacterial LPS.
