Interim report of results from an international collaborative study of the Proposed International Reference Preparation of porcine pancreatic kininogenase.

A collaborative study of the ampouled preparation of porcine pancreatic kininogenase, the Proposed International Reference Preparation (PIRP), was carried out, on behalf of the World Health Organization, by 19 laboratories in seven countries. The PIRP was studied using in vivo bioassays, immunoassays and in vitro enzyme assays involving natural protein substrate and small molecular ester and peptide substrates. An analysis of results obtained from a majority of the participating laboratories is presented. Comparison of the PIRP with the widely used Bayer house standard of porcine pancreatic kininogenase showed general agreement for estimates of relative activity, although differences were detected in some assay systems. The PIRP was shown to be stable and appears to be suitable to serve as an international reference preparation. Comparison of the PIRP with a preparation of highly purified human urinary kininogenase showed a wide diversity of estimates so that no general comparison of activities for these preparations is possible.