Anti-Pr3: serological and immunochemical identification of a new anti-Pr subspecificity

A monoclonal IgM(kappa) anti-Pr cold agglutinin occurring after a rubella infection is shown to have the 'new' anti-Pr subspecificity anti-Pr3. Pr3 determinants are found on cat and sheep erythrocytes which lack Pr1 and Pr2 determinants. By carbodiimide treatment of human erythrocyte glycoproteins, which causes intramolecular coupling of N-acetylneuraminic acid carboxyl groups and nucleophilic centers of the glycoprotein backbone, Pr3 antigen activity is strongly increased, while Pr1 and Pr2 determinants are inactivated.