IN-VIVO EXPRESSION OF INTERLEUKIN-1 RECEPTORS DURING VARIOUS EXPERIMENTALLY-INDUCED INFLAMMATORY CONDITIONS

Systemically administered interleukin-1 (IL-1) has been shown to prefe rentially bind to IL-1 receptors (IL-1Rs) in inflammation. Using radio labeled IL-1 alpha and molecular methods to assess gene expression for these receptors, the in vivo behavior of these receptors was investig ated in a number of experimental inflammatory conditions. The uptake o f I-125-labeled IL-1 alpha in inflammatory foci significantly correlat ed with the mRNA expression for the type I and type II IL-1Rs (P <.05) . Type II IL-1R mRNA showed a greater increase in expression than type I IL-1R mRNA, In neutropenic mice, inflammatory lesions, which are de void of granulocytes, significantly lower I-125-labeled IL-1 alpha upt ake (P < .001), and type II IL-1R mRNA expression (P <.005) was found. Thus, there is strong up-regulation of IL-1Rs at sites of focal infla mmation. Of interest, this mainly involved the type II IL-IR on granul ocytes, which is not involved in signal transduction.