CLASSIFICATION OF BLOOD-GROUP ANTIBODIES AS BETA M-2 OR GAMMA GLOBULIN

Abstract

Thirty selected blood-group antibodies (excluding anti-A and anti-B) have been classified as [beta]2M (19S gamma)globulin,gamma(7S gamma) globulin or matures, using the following three methods fractionation onaDEAE-cellulose column; indirect antiglobulin tests using specific anti-[beta]2M-globulin and anti-gamma-globulin sera; and treatment with 2-mercapto-ethanol. With only minor exceptions, results obtained with the three methods were in agreement. Most blood-group antibodies within the Le, MNSs and P systems appear to be "naturally occurring" and these were found to be [beta]2M globulin. Blood-group antibodies within the Rh, K and Jk systems, which had arisen after an antigenic stimulus, were usually gamma globulin but were occasionally [beta]2M globulin. Antibodies composed of [beta]2M globulin usually behave as agglutinins but may behave as incomplete antibodies (e.g. some examples of anti-Jka); conversely, antibodies composed of gamma globulin usually behave as incomplete antibodies but may behave as agglutinins (e.g. an example of anti-M). The ability to bind complement seems to be related more to the blood-group specificity of the particular antibody than to its molecular size. For example, anti-Jka, when composed either of gamma or [beta]2M globulin, seems invariably to bind complement, whereas potent anti-M or anti-Rh, whether composed of gamma or [beta]jM globulin, do not bind complement.