title: Expression of mouse beta 2-microglobulin in frozen and formaldehyde-fixed central nervous tissues: comparison of tissue behind the blood-brain barrier and tissue in a barrier-free region.
abstract: Previous work indicates that the weak expression in neural tissues of beta 2-microglobulin (beta 2-m) and major histocompatibility complex (MHC) class I gene products can be increased experimentally. Physiologic conditions in which greater neural MHC expression occurs are not well defined. Here we have asked whether protection from blood-borne antigens afforded by the blood-brain barrier is related to the lack of MHC expression. A rabbit antiserum raised against purified mouse beta 2-m was used in an immunocytochemical assay. The serum reacted strongly with lymphoid tissues and was inhibited by purified beta 2-m. No beta 2-m was detected in neurons or glia in any brain area examined. A barrier-free region, the area postrema, showed the same lack of neural cell staining. Blood vessel walls in the same sections were beta 2-m+. It is unlikely that these staining patterns are due to cell type-specific beta 2-m degradation, since frozen and formaldehyde-perfused, paraffin-embedded preparations gave similar results. Failure to detect beta 2-m in the area postrema suggests that passive exposure to environmental antigens, immunomodulators, or immunocompetent cells is not sufficient to induce neural class I expression. Rather, if increased expression of beta 2-m and class I occurs in vivo, additional stimulus is required.
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier; D001921:Brain / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D005260:Female; D005557:Formaldehyde; D005615:Freezing; D006652:Histological Techniques; D007421:Intestine, Small / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology; D008285:Major Histocompatibility Complex; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D010581:Peyer's Patches / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D001613:beta 2-Microglobulin / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D001613:beta 2-Microglobulin; D005557:Formaldehyde