Expression and localization of p80 and p68 interleukin-1 receptor proteinsin the brain of adult mice

The biological effects of interleukin-l (IL-l) are mediated by two distinct receptors, the p80 type I TL;land p68 type IT IL-1 receptor proteins (IL-1 RI and IL-1RII, respectively), both of which have been recently co-localize d to the: growth hormone synthesizing cells of the adenohypophysis. Previou s studies have shown that IL-l can bind to specific structures in the centr al nervous system, but the distribution of IL-1R1 and IL-1RII proteins in t he adult mouse brain has not been reported. Here we have used immunohistoch emistry to study the expression, distribution and cellular localization of both isoforms of the IL-I receptor proteins in the adult mouse brain. Using a combination of processing techniques (AMeX fixation and cryosectioning), we have immunolabeled brain sections for each isoform of the IL-IR. Both i soforms are expressed in the CNS, particularly in neuronal soma of the gran ular layer of the dentate gyrus and pyramidal cells of fields CA1-CA4 of Am mon's born of the hippocampus, in epithelial cells of the choroid plexus an d ependymal layer, and in neuronal soma of Purkinje cells of the cerebellum . The IL-1RII isoform, but not LL-IRI, is expressed in specific neuronal so ma and proximal cell processes of neurons of the paraventricular gray matte r of the hypothalamus. These immunohistochemical data directly demonstrate the neuronal expression of both IL-1R proteins in situ. The distribution an d cellular localization of IL-1R proteins in the CNS provide a molecular ba sis for understanding reciprocal interactions between the immune system and the brain. (C) 1999 Elsevier Science B.V. All rights reserved.