The Nature of Incomplete Erythrocyte Antibodies

On “Incomplete” Anti-Rh Antibodies: Mechanism of Direct Agglutination Induced by Mercaptoethanol*

“…Our data, although not in accord with the original postulate of Pirofsky and Cordova (8,9), do suggest alternative explanations for the phenomenon they described.…”

“…With ME-induced agglutination, the second stage of the isoantibody-antigen reaction, agglutination of the red cell mass may perhaps be a nonspecific process influenced by the suspending medium or by alteration of the red cell surface. 9 The latter suggestion is supported by the observation of Davis, Green, and Tymms (16), in studies by electron microscopy, that changes on the red cell surface may be brought about by sensitization with anti-D. In addition, it is generally agreed that enzymes, by altering the red cell surface, enhance agglutination of sensitized cells.…”

“…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.…”

“…Pirofsky and Cordova (8,9), c correlation between the antiglobulir ability of ME to induce saline actii complete anti-Rh sera (Table I). as in subse-eleven sera tested had significant saline activity in 3.s used, agglu-the presence of ME.…”

“…A more recent approach concerns the orientation of the combining sites of the incomplete antibody molecule. Pirofsky and Cordova (8,9) postulated that the incomplete anti-Rh antibody molecule has one reactive group available for lattice formation and one or more potentially reactive groups that are not available because of steric inaccessibility. Their experiments showed that in the presence of mercaptoethanol incomplete anti-Rh serum produced direct saline agglutination of the appropriate cells.…”