Heterogeneity of anti-A and anti-B monoclonal reagents. Agglutination of some weak ABH erythrocyte variants and recognition of synthetic oligosaccharide and tissue antigens.

Eight anti-A and seven anti-B monoclonal reagents were tested in parallel, with normal and weak ABH red cell phenotypes. A whole range of different reactivity patterns was found, but by making a comparison with the results obtained using polyclonal standard reagents, two major categories of reagents were distinguished: (a) stronger and more specific reagents, and (b) reagents similar to, or weaker than, the standard polyclonal controls. The analysis of the specificity of the reagents by tissue fluorescence staining and reactivity with synthetic oligosaccharides and purified glycolipids confirmed the existence of broad and restricted specificities. Two kinds of anti-A1 reagents are described. One related to type 3/4 structures, which stains the Golgi apparatus, and another with broad anti-A specificity which cross-reacts with 'A-like' structures. The inhibition of anti-A reagents with salivas and synthetic oligosaccharide antigens gave parallel results for the secretor salivas and the difucosylated A antigens.