A new variant of blood group A. Apae.

A new variant of blood group A, termed Apae, was found as an inherited characteristic in three unrelated white families. Apae was distinguished from other A variants by its agglutination and absorption-elution reactions with only certain human anti-A and -A,B serums, by the red cells that reacted with anti-A from Helix pomatia without the need for enzyme treatment, by enhancement of the latter reaction with bromelinization, and by the presence in the serum of an anti-A of normal avidity and titer. Apae also reacted strongly with a recently discovered anti-A agglutinin derived from the seaweed Codium fragile, subspecies atlanticum, but not with a series of other anti-A lectins. It was concluded that Apae cells express only part of the normal A antigen and that the anti-A present in the serum does not have an anti-Apae component.