MRC OX-43: a monoclonal antibody which reacts with all vascular endothelium in the rat except that of brain capillaries.

A mouse monoclonal antibody, MRC OX-43, has been shown to label vascular endothelium in all tissues of the rat except that of brain capillaries. Using immunoperoxidase staining, the antigen was shown to be expressed on the luminal surface of blood vessels. In addition, this antibody recognized a surface antigen on circulating erythrocytes and some macrophage populations, namely all those in the peritoneal cavity and a subset of alveolar macrophages. The antigen recognized by this antibody was identified on macrophages by metabolic and cell surface labelling followed by immunoprecipitation and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and found to be a surface protein of 90,000 MW.