Studies on erythroblastosis fetalis with special reference to the cross-reacting antibody
In 1960, the first proven case among Koreans babies of Rh-sensitized and five cases of ABO-sensitized erythroblastosis fetails were reported by the present author. Attention ws paid to the fact that all of those ABO-cases happened exclusively in group-O mothers. Seeking the explanation of this phenomenon, the
author was interested in the role of the so-called "Cross- reacting antibody", which importance in the development of ABO-erythroblastosis fetalis was postulated by Wiener and Zuelzer(1955).
Employing the technique of antibody-absorption and elution introduced by Dodd(1952) the author made the following observations using both clinical materials of Koreans population and experimental animal materials.
1. Antibody responses to a same antigen stimulation was greater in group-O persons than in any other group persons, and this was true in both natural and immune antibody productions.
2. Group-O persons might possess a so-called cross-reacting antibody, anti-C, in addition to the ordinary anti-A and anti-B; and its frequencies among Koreans were 70 to 77% in male and 65 to 80% in pregnant female.
3. The cross-reacting antibody reacted better at 37C than at 4C and better in colloidal medium than in saline medium.
4. The cross-reacting antibody reacted best with an indirect Coombs techniqeu among the ordinary three titration techniques; and in this regard this antibody belonged to an incomplete antibody.
5. In contrast to immune anti-A or anti-B sera, the cross-reacting antibody was neutralized by soluble group specific substances but this phenomenon did not happen on an immune animal origine cross-reacting antibody.
6. It was demonstrated that blood-free placental emulsion absorbed hemagglutinins in vitro including the cross-reacting antibody; and the same phenomenon appeared to occur in vivo as demonstrated in a group-A fetal placenta delivered from a group-O
These observations were discussed to find the possible role of the cross-reacting antibody in the pathogenesis of ABO-erythroblastosis fetalis and the author reached the conclusion that the reasons why ABO-erythroblastosis fetails is apt to occur in cases of group-O mothers would be: they are prone to produce more hemagglutinins than any other group persons, in general, and they produce so-called cross-reacting antibody readily, which would not be possibly produced in any other group persons.
Furthermore, the cross-reacting antibody possesses many immunohematologically advantageous characteristics which would induce an erythroblastosis fetalis. On the other hands the reasons why all group-O mothers do not develop erythroblastosis
fetalis in their heterospecific pregnancies would be: the cross-reacting antibody is absorbed by placenta, a fact which is quite different from that in the cases of Rh-antibodies, and the cross-reacting antibody is neutralized by soluble group specific substances in the fetus. These fetal protective mechanisms would weaken the offending potency of the cross-reacting antibody.