| In autoimmune demyelinating diseases such as multiple sclerosis (MS) and peripheral neuropathies, breaching of blood-brain/blood-nerve barrier preceded that of pathological changes and clinical symptoms (Kermode et al., 1990), suggesting an immunological attack on the microvascular endothelial cells. Autoimmune imunoglobulins (Tanaka et al., 1987 Tsukada et al., 1989 Tintore et al., 1996 Trojano et al., 1996) and autoreactive T-cells against endothelial antigens (Tsukada et al, 1993) have been reported in diseases including MS, but the nature of these antigens have not been well described. Additionally, autoreactive leukocytes specific to myelin components have been also reported in MS. In this study, we examined the sulfated glucuronic acid epitope (SGA, HNK-1, CD-57) epitope and neural cell adhesion molecule (NCAM, CD-56), shared determinants between myelin and its microvasculature, that could serve as sites of an autoimmune attack.Although the SGA epitope has been shown to be restricted to the adhesion molecules of the nervous system and to natural killer cells, it also has been shown to exist on microvascular endothelial cells of the rat brain (Miyatani et al., 1990) and cultured bovine brain endothelial cells, presented by sulfated-glucuronosyl glycolipids (SGGLs Kanda et al., 1994). Little has been described about the protein carriers of the SGA epitope. In this study, we demonstrated that three glycoprotein membrane components of cultured bovine brain endothelial cells (BMECs) presented the SGA epitope--SGA-220, SGA-120, and SGA-80. By stripping the blot and relabelling with a monoclonal anti-NCAM (OB-11), we identified SGA-220 to be NCAM-220. Additionally, BMECs also expressed an NCAM-125 isoform. Isoelectric focusing and SDS-PAGE showed NCAM 220 with an isoelectric point of 3.5, NCAM 125 with an isoelectric point of 5, and SGA-120 with an isoelectric point of 5. Reverse transcription PCR using homologous NCAM primers, followed by cloning and sequencing of the amplified fragment, confirmed the expression of NCAMs in BMECs. Thus, BMECs have the capacity to express NCAM 220, NCAM 125, SGA 120, and SGA 80 in addition to having SGGLs.Neither NCAM 220 nor its SGA epitope was responsive to IL-1In conclusion, the present report provided evidence for four molecules, NCAM A (SGA-220), NCAM B, SGA-120, and SGA-80, as shared determinants of myelin and the vasculature. NCAM A and its SGA modification were not regulated by the cytokine IL-1... |
