“…Pirofsky and Cordova (8,9), on the basis of this ME-induced agglutination, postulated that incomplete anti-D is a bivalent antibody. They suggested that only one of the combining sites of the incomplete antibody is available for interaction with the red cell antigen and that alteration of the tertiary structure of the antibody molecule by ME exposes the previously hidden site, making it available for agglutination.…”