USE OF THE MAIEA TECHNIQUE TO CONFIRM THE RELATIONSHIP BETWEEN THE CROMER ANTIGENS AND DECAY-ACCELERATING FACTOR AND TO ASSIGN PROVISIONALLY ANTIGENS TO THE SHORT-CONSENSUS REPEATS

The MAIEA (monoclonal-antibody-specific immobilisation of erythrocyte antigens) assay has recently been developed for the assignment of red cell antigens, recognised by human alloantisera, to particular membran e components of the red cell membrane [17]. This technique detects tri molecular complexes formed by the reaction of a human antibody and a m ouse antibody with a particular red cell protein. A positive reaction, in an ELISA-type detection procedure, occurs if the epitopes to the h uman and mouse antibodies are present on the same membrane component b ut at different regions. In this report, we show how the MAIEA assay c an be used to confirm the relationship between Cromer system antigens and the complement-regulatory protein, decay-accelerating factor (DAF, CD 55). In addition, the location of the antigens along the protein i s postulated by using three anti-DAF monoclonal antibodies with specif icities to different regions of DAF. Tc(a) and Es(a) are assigned prov isionally to the first short-consensus repeat (SCR), UMC to the second SCR, Dr(a) to the third SCR and Cr(a), WES(a) and WES(b) to the fourt h SCR or to the serine/threonine rich region of the DAF protein.