DIFFERENTIAL EXPRESSION OF AN ENDOTHELIAL BARRIER ANTIGEN BETWEEN THECNS AND THE PNS

A monoclonal antibody to an antigen (EBA) expressed by neural endothel ial cells (EC) was used to investigate any difference in the distribut ion of EBA between the CNS and PNS. Pre-embedding ultrastructural cyto chemistry of rat sciatic and optic nerves was undertaken using anti-EB A, detected with a silver-enhanced gold-conjugated secondary antibody. LM immunocytochemical localisation of EBA was also performed using an HRP-conjugated secondary antibody. EC of pial and parenchymal optic n erve vessels were strongly immunopositive for EBA. Vessels of the dura were negative. At the EM level EBA was observed on the EC luminal sur face. In contrast, EC of sciatic nerve were either negative or only we akly immunopositive. The molecular characteristics and function of EBA are largely unknown. Therefore the functional significance of the pre sent findings remains to be determined.