Isolation of membrane components associated with human red cell antigens Rh(D), (c̄), (E) and Fy^a

Abstract

The isolation of human red cell membrane components associated with Rhesus (Rh) and Duffy (Fy) blood group antigen expression has been largely frustrated due to the small quantities in the membrane^1–5 and their probable integral membrane nature requiring lipid for optimum antigen expression^6–10. The disadvantage of reported immunoaffinity techniques for investigating Rh(D) has been non-specific adsorption which complicates identification of antigen-associated components^11,12. Thus, Rh(D) has been attributed to a 7,000 molecular weight (MW) fraction¹¹ and a subpopulation of band 3 (ref. 13; MW ∼90,000)¹². We report here a technique, with negligible non-specific adsorption, for the isolation of blood group antigen–antibody complexes and their analysis by SDS-polyacrylamide gel electrophoresis (PAGE). Radiolabelling techniques facilitated identification of antigen-associated membrane components. We found that expression of Rh(D), (c̄) and (E) was associated with a component(s) of 28,500 apparent MW, with additional 50,000- and 68,000-MW components associated with Rh(D). In contrast, Fy^a is associated with 39,500- (possibly PAS 2), 64,000- and 88,000-MW components, the latter having a similar mobility in SDS-PAGE to band 3.