Characterization of maternal isoagglutinins in ABO hemolytic disease of the newborn.

By Susis W. FONG, ARLENE NUCKTON AND H. H. FUDENBERG M ANY SEROLOGIC tests have been advocated as aids for the antenatal diagnosis of ABO hemolytic disease of the newborn (ABO HDN). The majority of the tests currently used in most hospital clinical laboratories for this purpose make use of certain serologic properties that differentiate the isoagglutinins into two groups. Although both groups probably arise as the result of antigenic stimulation, the early literature has termed them “immune” and “naturally occurring.” The so-called “immune” isoantibodies, which have been implicated in ABO HDN, can be distinguished from the “naturally occurring” variety by their ability to agglutinate A1 or B cells suspended in AB serum even after partial neutralization by soluble specific blood group substances A and B,1 hemolyze A1 or B cells in the presence of complement,2 and react with group A pig (A1) cells.:i The clinical importance of establishing the presence of ABO HDN antenatally, thus alerting the physician to the possible need for exchange transfusion of the newborn, led us to evaluate the relative merits of the different serologic procedures used to detect “immune” isoantibodies. This report describes and compares results of such tests on the sera of blood group 0 mothers of infants with and without ABO HDN. Comparative tests were also performed on the isolated ‘y2-(7S) globulin and whole serum of mothers of infants with ABO HDN.