Functional analysis of MHC class I molecules in the neuronal cells of central nervous

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In order to elucidate a role of MHC molecules in the central nervous system (CNS), we have examined the expression of classical and non-classical class I molecules in the CNS of C57BL/6 mice by using RT-PCR and immuno-histochemistry. In class I molecules, although H2-K and H2-D transcripts were found by RT PCR analysis, these proteins were mainly localized in endothelial cells and choroids plexus cells by immuno-histochemical study using an anti-class I antibody. The staining of neuronal cells was faint or weak, and the characteristic distribution of class I MHC molecules was not recognized in neuronal cells. In contrast, non-classical class I proteins were localized mainly in the neuronal cells. The strong staining of H2-Qa 1 protein was observed In the nerve cells localized in the 5th and 6th layer of cerebral cortex, hippocampus and the tuberal nucleus. These data suggested that non-classical MHC class I molecules may have special roles in nerve cells of CNS. It was reported that th … More ere are over 10 genes coding the non-classical class I molecules in mouse, however, the exact number or gene structures had not been determined. We estimated the 17 non-classical class I genes from the draft sequence of mouse genome by computerr analysis, and RT-PCR analysis was performed on total RNAs extracted from cerebral cortex, hypothalamus, cerebellum, thymus, small intestine, liver, kidney and spleen. Eight non-classical MHC class I transcripts were observed in cerebral cortex, hypothalamus and cerebellum, although the seven among eight genes were expressed in all the tissues so far examined. The H2-M5 gene is expressed specifically for CNS. The expression of eight non-classical MHC class I molecules may suggest an important role of these molecules in the remodeling and plasticity of connection of nerve cells or in some immune responses in the CNS. To determine exact roles of non-classical MHC class I molecules, the production of the H2-M5 gene targeting mouse and the H2-Qa1 overexpressing mouse are now in progress. Less