Identification by Immunoblotting of the Erythrocyte Membrane Sialoglycoproteins That Carry the Vw and Mur Antigens

Immunoblotting of the separated membrane components of MiI erythrocytes with anti-Vw identified a band of Mr 40,000 with a mobility close to that of beta-sialoglycoprotein corresponding to the abnormal alpha-sialoglycoprotein present in MiI cells. A comparison of results obtained when MiIII erythrocytes were immunoblotted with anti-Mur, anti-s and the monoclonal antibody R1.3, indicated that the Mur antigen is located on the abnormal delta-sialoglycoprotein of Mr 36,000 in MiIII erythrocytes. Prior treatment of MiI erythrocytes with neuraminidase resulted in an increase in the intensity of staining of the anti-Vw reactive component. This was consistent with the enhanced reactions observed in haemagglutination tests with neuraminidase-treated erythrocytes. The mobility of the Vw component was reduced when erythrocytes were pre-treated with low concentrations of neuraminidase but increased when higher concentrations of neuraminidase were used.