Le(a) antigen

The Le(a) antigen is part of the Lewis system and is a plasma glycosphingolipid produced by gut epithelium and passively adsorbed onto the red cell membrane. Antibodies to Lewis antigens usually occur without known red cell stimulus and they are predominantly IgM. Transfused donor RBCs shed their own Lewis antigens and assume the phenotype of the recipient within a few days of transfusion (released antigens are then easily neutralized by the anti-Lewis antibodies in the recipient’s plasma). Hemolytic transfusion reactions and hemolytic disease of the fetus or newborn due to Lewis antibodies are rare. It is not considered necessary to find Le(a)-negative donor blood.