A monoclonal antibody applicable for determination of C-peptide of human proinsulin by RIA.

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 (Kas = 1.1 x 10(9) l/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).