THE MONOCLONAL ANTIBODY-SPECIFIC IMMOBILIZATION OF ERYTHROCYTE ANTIGENS ASSAY (MAIEA) IN THE INVESTIGATION OF HUMAN RED-CELL ANTIGENS AND THEIR ASSOCIATED MEMBRANE-PROTEINS

The monoclonal antibody-specific immobilization of erythrocyte antigen s (MAIEA) technique is an immunoassay devised primarily for locating b lood group antigens on specific red-cell membrane proteins. The assay involves the incubation of intact red cells with two antibodies, one h uman alloantibody, the other a nonhuman antibody, usually a rodent mon oclonal antibody, but polyclonal antibodies of rabbit origin have been utilized. For a positive result, both antibodies must bind to the sam e membrane protein. The red cells are lysed, the membrane solubilized and the trimolecular complex of two antibodies and membrane protein is captured in a well coated with goat antirodent (or rabbit) immunoglob ulin. The immobilized complex is then detected by the use of peroxidas e-conjugated goat antihuman (or rodent) immunoglobulin. Negative resul ts, due to mutual blocking between the human and animal antibodies whe n their epitopes are close together on the same molecule, have permitt ed a degree of localization of epitopes on some proteins. This has bee n most effective in the mapping of Cromer blood group system antigens on the complement control protein domains of decay-accelerating factor (DAF, CD55), but has also proved informative in the clustering of ant igens on the Lutheran and Kell glycoproteins. MAIEA is an effective to ol for the identification of antibodies to Knops-system antigens on co mplement receptor 1 (CR1, CD35) in immunohaematology reference laborat ories. These antibodies are clinically unimportant, but must be identi fied before they can be ignored for transfusion purposes.