Some monoclonal antibodies raised with a native protein bind preferentially to the denatured antigen.

Recent studies with monoclonal antibodies directed against different epitopes of the beta 2-subunit of Escherichia coli tryptophan synthase have shown that some of these antibodies bind rapidly in solution to the native protein; others bind very slowly to native beta 2 in solution while they recognize quite rapidly this antigen adsorbed on a microtitration plate. In the present work, an enzyme-linked immunosorbent assay competition test with either the native or a denatured form of the antigen has been developed. It allowed us to show that the rapidly binding antibodies recognize epitopes present on the native protein while those which react very slowly in solution bind preferentially to the denatured form of the protein. These results prompted us to emphasize how important it is, in the characterization of antibodies, to ascertain that the antigen they recognize remains native in the specificity test.