Chemical Resolution of an Epitope Recognized by Blood Group Antibodies Capable of Binding Both A and B Red Blood Cells.

Chembiochem : a European journal of chemical biology 2024 Sep 02

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The high specificity of human antibodies to blood group A and B antigens is impressive, especially when considering the structural difference between these antigens (tetrasaccharides) is a NHAc versus a hydroxyl group on the terminal monosaccharide residue. It is well established that in addition to anti-A and anti-B there is a third antibody, anti-A,B capable of recognizing both A and B antigens. To analyze this AB specificity, we synthesized a tetrasaccharide, where the NHAc of the A antigen was replaced with an NH2. This NH2 group was then used to attach the glycan to an affinity resin, creating an AB epitope (ABep) adsorbent where the critical site for recognition by A and B antibodies was not accessible, while the rest of the (conformationally compact) tetrasaccharide remained accessible. Anti-ABep antibodies were then isolated from blood group O donors and found to have expected A,B specificity against immobilized and red cell bound synthetic antigens, including ABep, and were able to agglutinate both A and B red cells. The amount of these anti-ABep (anti-A,B) antibodies found in the blood of group O donors was comparable to levels of anti-A and anti-B found in group B and A individuals. Using STD-NMR the location for the AB epitope on the tetrasaccharide was found. © 2024 Wiley-VCH GmbH.

Citation

Polina Obukhova, Tatiana Tyrtysh, Svetlana Tsygankova, Alexander Paramonov, Elena Gordeeva, Nadezhda Shilova, Alexander Lipatnikov, Maria Sokolova, Stephen Henry, Emin Salimov, Nicolai Bovin, Ivan Ryzhov. Chemical Resolution of an Epitope Recognized by Blood Group Antibodies Capable of Binding Both A and B Red Blood Cells. Chembiochem : a European journal of chemical biology. 2024 Sep 02;25(17):e202400430