Expression and localization of p80 and p68 interleukin-1 receptor proteins in 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-1RI and IL-1RII, respectively), both of which have been recently co-localized to the: growth hormone synthesizing cells of the adenohypophysis. Previous studies have shown that IL-l can bind to specific structures in the central nervous system, but the distribution of IL-1R1 and IL-1RII proteins in the adult mouse brain has not been reported. Here we have used immunohistochemistry 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 isoforms are expressed in the CNS, particularly in neuronal soma of the granular layer of the dentate gyrus and pyramidal cells of fields CA1-CA4 of Ammon's born of the hippocampus, in epithelial cells of the choroid plexus and 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 soma and proximal cell processes of neurons of the paraventricular gray matter of the hypothalamus. These immunohistochemical data directly demonstrate the neuronal expression of both IL-1R proteins in situ. The distribution and cellular localization of IL-1R proteins in the CNS provide a molecular basis for understanding reciprocal interactions between the immune system and the brain. (C) 1999 Elsevier Science B.V. All rights reserved.