Antigen Presentation in an Artificial and Cell Membrane: Blood Group A Glycan Recognition.

Glycosphingolipids (GSL) are functionally important components of the cell membrane and recognition of their glycan "head" by the immune system is a key part of normal and pathological processes. Recognition of glycolipid antigens on a living cell, their structure, "context" (microenvironment and clustering), presentation including orientation and distance from the plasma membrane, as well as molecular dynamics are important. GSL antigens are targets for the development of anticancer vaccines and therapeutic antibodies, therefore, control of the presentation of their glycans by synthetic methods opens up new possibilities in medicine. In this work, we synthesized 13 GSL analogues as function-spacer-lipids (FSLs) with the same head (blood group A tetrasaccharide, ABO system) but each either differing in the structure of the lipid tail, or the length of the region between the head and the tail, or cluster organization of the head (from 2 to 4 tetrasaccharides in a cluster). The insertion of these FSLs into an artificial and erythrocyte membranes was compared, and their interaction with antibodies was studied, including erythrocyte agglutination. The results give further insight into knowledge of the membrane presentation of GSLs (some results can be extrapolated to glycoproteins) and factors involved in their interaction with antibodies.