Specificity of Monoclonal Anti-Human Insulin Antibodies

To define the specificity and epitope of five monoclonal antibodies (MoAbs) to human insulin, binding studies with artificially modified insulins and a number of native insulins were done. Epitopes on the A-chain (A4, A8–A10) and on the end of the B-chain (B30) could be identified. For two MoAbs, substructures of the amino acid B30 were found, which were essential for binding (hydroxyl and methyl groups of B30). In contrast to most antisera, MoAbs to human insulin show high specificity. However, as the study shows, the specificity is not absolute. With suitable artificial epitope modifications, cross-reaction can be seen. Two of the MoAbs used here show sufficient specificity to discriminate between insulin and proinsulin.