Gamma-A-blood group antibodies.

The serological characteristics of gammaA-anti-A and anti-B were studied using, as a source, either colostrum, or fractions relatively rich in gammaA obtained from selected potent antisera. gammaA-anti-A and anti-B were never hemolytic nor did they sensitize red cells to agglutination by anticomplement globulin sera. gammaA-anti-A, like gammaG-anti-A and unlike gammaM-anti-A was unaffected by heating at 56 degrees C for 3 hr. On the other hand in the following three characteristics the behavior of gammaA fell between that of gammaG- or gammaM-anti-A: sensitivity to inactivation by 2-mercaptoethanol, ease of neutralization by A substance and degree of enhancement of agglutination in a medium of serum rather than saline. The agglutination produced by gammaA-anti-A was regularly enhanced by addition of anti-gammaA-globulin serum. In searching for gammaA-blood group antibodies of other specificities the following sera were tested: anti-D (32 examples); anti-c (2 examples); anti-Le(a) or -Le(b) (3 examples); anti-K (3 examples); anti-Fy(a) (3 examples), and anti-Jk(a) (3 examples). Only 3 sera, all containing anti-D, sensitized red cells to agglutination by anti-gammaA. There were no discrepancies between results obtained with four different anti-gammaA-globulin sera. Approximately half the sera were fractionated on DEAE-cellulose, and the fractions rich in gammaA tested for their ability to sensitize red cells to agglutination by anti-gammaA; no additional examples of gammaA-antibodies were detected. One of the three examples of gammaA-anti-D appeared in the serum of a woman during the course of deliberate reimmunization. gammaA-anti-D appeared only after three intravenous injections of red cells although the gammaG-anti-D titer rose considerably after a single injection. 3 yr after a fourth injection of Rh-positive cells gammaA-anti-D, as well as gammaG-anti-D, was still present in the serum.