EXPLORING ANTIBODY POLYSPECIFICITY USING SYNTHETIC COMBINATORIAL LIBRARIES

Extensive mapping studies for seven antigen-antibody interactions have been carried out using both individual analogs and peptide libraries. With competitive ELISA, these studies have revealed that monoclonal a ntibodies exhibit a broad range of specificities, from antibodies that recognize only conservative substitutions for 1-2 positions of the an tigenic determinant, to antibodies that recognize sequences that are c ompletely unrelated to the parent antigen with comparable affinities. Synthetic combinatorial libraries, containing millions of peptide sequ ences, permit a more systematic and rapid evaluation of the extent of multiple-binding specificities of monoclonal antibodies than individua l analogs. The peptide libraries used here comprise mixtures of compou nds having specifically defined positions and mixture positions. The s ame diversity of sequences in different formats, which differ by the n umbers of positions singularly defined and different locations defined within the sequence, can be examined. Comparison of the screening res ults, selection criteria of the most active mixtures, and different ap proaches used for the deconvolution of active individual compounds are discussed. Synthetic combinatorial libraries greatly facilitate the u nderstanding of antigen-antibody interactions at the amino acid level and will assist in the development of improved immunodiagnostics.