Production and characterization of monoclonal antibodies to human pancreatic elastase 2.

Three murine monoclonal antibodies (MAbs) against human pancreatic elastase 2 (ELS-2) were produced by hybridomas obtained from the fusion of murine myeloma cells, P3X63-Ag8.-653, with the splenocytes of mice immunized with recombinant human proELS-2 (r-proELS-2) and purified natural ELS-2. These MAbs were found to recognize the different epitopes of ELS-2 based on a competitive binding assay. In addition, one of the MAbs, E19, reacted with the activation peptide of ELS-2. Western blot analysis performed under nonreducing conditions indicated that all MAbs bound only to ELS-2 in pancreatic juice in addition to natural ELS-2. Reduced ELS-2 on a Western blot could not be detected with E19, indicating that the activation peptide remained attached to active ELS-2 via a disulfide bond even after tryptic activation. Another MAb, B4, inhibited the enzymatic activity of ELS-2, indicating that B4 recognized the active site or its vicinity to ELS-2.