Use of the MAIEA assay to demonstrate that Fy3 is on the same glycoprotein as Fy6, Fya, and Fyb

The monoclonal-antibody immobilization of erythrocyte antigens (MAIEA) assay is a technique that detects trimolecular complexes formed by a human antibody and a mouse monoclonal antibody with specific red cell epitopes. This enzyme-linked immunoadsorbent assay test gives a positive reaction when two different epitopes on the same membrane protein are separately recognized by human and mouse antibodies. In this study, the MAIEA test was used to determine if the Duffy system antigen Fy3 is on the same membrane protein as Fy6. The well-established location and relationship of Duffy blood group antigens Fy^a, Fy^b, and Fy6 were again confirmed by the MAIEA assay, and those facts were used to standardize a variation of the assay to establish the relationship between Fy3 and Fy6 using red cells with various Fy phenotypes. The MAIEA assay generated high absorbance values when Fy6 and Fy^a (or Fy^b) antigens were evaluated. Similarly, high absorbance values were seen when Fy3 and Fy6 antigens were tested using Fy(a+b+), Fy(a+b–), and Fy(a–b+) red cells. The MAIEA assay is a valid technique for detecting Duffy system antigens. By this technique, it was shown that Fy3 and Fy6 antigens are carried on the Duffy glycoprotein D and by extension that Fy3 is also located on the Duffy glycoprotein D.