'Weak A' phenotypes. Relationship between red cell agglutinability and antigen site density.

Abstract

Thirty-five weak A samples including fourteen A(3), eight A(x), seven A(end), three A(m) and three A(e1) were studied in order to determine their A antigen site density, using an IgG anti-A labelled with (125)I. The values obtained ranged between 30,000 A antigen sites for A(3) individuals, and 700 sites for the A(e1) red cells. The hierarchy of values observed made it possible to establish a quantitative relationship between the red cell agglutinability of these phenotypes measured under standard conditions, and their antigen site density.