A Monoclonal Antibody Applicable for Determination of C-Peptide of Human Proinsulin by RIA

Abstract

BALB/c, (BALB/c x B10.A)F₁ and (BALB/c x B10)F₁ hybrid mice were immunized with C-peptide of human proinsulin. The (BALB/c x B10.A)F₁ hybrids were the best responders and yielded 3 hybridomas secreting specific monoclonal antibodies. One of them, C-PEP-01, bound the C-peptide with high affinity (K_as = 1.1 x 10⁹l/mol), cross-reacted fully with human proinsulin but not with insulin, glucagon or somatostatin and apparently recognized the regions of C-peptide comprising amino acid residues 8-13 and 25-31. A RIA system could be set up employing this monoclonal antibody suitable for estimation of C-peptide concentrations in a diagnostically useful range (1-50 ng/ml).