ABO Blood System: Biosynthesis of Agglutinogenic Alkaline and Non-Agglutinogenic Acid Glycotopes of A and B Antigens at Different pHs of the Culture Medium.

The biosynthesis of agglutinogenic and adsorbing groups A and B glycotopes of the erythrocyte's membrane is mediated by the activity of specific glycosyltransferases. This study aimed to assess the nature of the biosynthesis of A and B antigenic glycotopes, depending on the pH of the medium during the cultivation of erythrocytes, and the antigenic (transferase) characteristics of the donor serum of the other group. Monoclonal antibodies (Mabs) were obtained from IGBRL under Program IV of the International Workshop on Monoclonal Antibodies and Red Blood Cell Antigens. Biosynthesis was performed using erythrocytes, fresh serum, medium 199, and an antibiotic solution. The agglutinogenic characteristics of 11 out of 33 samples changed by the end of the cultivation period due to the acquisition of additional agglutinogen corresponding to the donor serum. None of the samples lost their inherent agglutinogen due to its absence in the donor serum. Four of six samples of O(I) erythrocytes acquired the ability to be agglutinated by anti-A reagents, especially by the polyclonal anti-A, and the manifestation of agglutination depended on the reaction time. Two of the three samples with initial A(II) agglutinogenic specificity added to the donor serum with Bc'+ characteristic of the erythrocytes acquired this characteristic. However, none of the five A(II)Ac'+ samples cultured in the serum of Ac'-O(I)Ac'-Bc'+ and O(I)Ac'-Bc'- donors lost their inherent earlier Ac'+ characteristic. The investigation of the inhibitory ability of alkaline and acidic glycoconjugates isolated from membranes revealed that alkaline Alp-00 and Alp-1 glycotopes isolated from glycolipids had the highest inhibitory activity, and the degree of inhibition of polyclonal anti-A antibodies was even higher than that of monovalent BRIC-131. This study showed the possibility of the biosynthesis of specific non-agglutinogenic A and B glycotopes under the influence of a different group's serum as a source of the corresponding transferase.