The natural anti-Gal antibody, the B-like antigen, and human red cell aging.

The specificity of antibodies bound to senescent red cells has been assessed by elution analysis with various carbohydrates. A large proportion of these antibodies bound to normal senescent red cells and some pathologic red cells display a specificity to alpha-galactosyl carbohydrates. Anti-Gal (anti-alpha-galactosyl antibody) constitutes as much as 1% of circulating IgG in humans; it interacts specifically with Gal alpha 1----3Gal glycosidic structures. This study suggests that a cryptic B-like Gal alpha----3 Gal epitope is exposed on red cells as they age in the circulation and subsequently binds the anti-Gal antibody. Furthermore, it was hypothesized that, in some hemolytic disorders, pathologic alterations in the red cells may lead to premature exposure of this antigen, and, hence, to increased extravascular lysis observed in such diseases as beta-thalassemia and sickle cell anemia.