Immunochemical characterization of interactions between circulating autologous immunoglobulin G and normal human erythrocyte membrane proteins

Autologous immunoglobulin G present during electrophoresis of human erythrocyte membrane proteins influenced the electrophoretic mobility of some of the proteins. Different types of non-ionic detergents were used for solubilization of the membranes and together with experiments using dimyristoylphosphatidylcholine-derived erythrocyte membrane vesicles this indicated that IgG binds to spectrin, ankyrin, and band 3 protein. The binding was independent on proteolysis and not due to unspecific protein-protein interactions. Immunoblotting experiments also showed binding to polypeptide bands in the spectrin and ankyrin regions and demonstrated the presence of erythrocyte-associated IgG. The reactivity may be due to natural autoantibodies involved in the clearance of cellular debris in vivo. Whether the observations are of relevance for the putative immune-mediated clearance of old erythrocytes from the circulation remains to be established.