Development and characterization of antibodies to carbohydrate antigens.

Antibodies to carbohydrate antigens are critical for the study of bacteria, tumors, blood groups, and cell-cell adhesion interactions; for the analysis of viral, hormone, and toxin receptors; and, finally, for analysis of the glycosylation of recombinant proteins. However, antibodies to carbohydrate structures are more difficult to develop because of the T-cell-independent response to carbohydrates. This can result in the production of low affinity and difficult to work with IgM antibodies to these molecules. Screening technologies that include IgM antibodies can cause selections of antibodies with low-affinity binding sites because of the net avidity enhancement. Unfortunately, the low-affinity binding site can also have a similar affinity for unwanted structures. Production of antibodies using cellular extracts can result in antibodies that react with multiple related structures, and therefore the resultant bioassays have sensitivity or specificity problems. Protein conjugates of saccharides for the production of polyclonal and monoclonal antibodies to carbohydrate structures can be used to solve these problems. For monoclonal antibody development to oligosaccharides, mapping with closely related saccharides allows the determination of the areas of the saccharide to which the antibody binds so that conclusions can be made concerning which saccharide structures will cross-react. Determination of the reactivity of the produced antibodies with related saccharide structures is essential prior to utilization.