[Epitope specificity of hemagglutinating monoclonal anti-A-antibodies]

Fine epitope specificity of three anti-A monoclonal antibodies (MA) 1H410, 3F9, and 44F9 was studied by: 1) direct MA binding to synthetic oligosaccharides (OS) linked to polyacrylamide matrix, and 2) inhibition of MA binding to natural antigen by synthetic OS and their polyacrylamide conjugates. It has been established that the antigen binding site of MA 1H10 is specific for tetrasaccharide A (type 3), whereas MAs 3F9 and 44F9 recognize trisaccharide A, the contribution of alpha-L-fucosyl residue being insignificant in the case of 44F9 binding. The correlation of the MAs epitope specificity with their ability to agglutinate red blood cells of A1 and weak A subgroups is discussed.