Development of a peptide-based sandwich elisa for human tissue prokallikrein with no cross-reactivity from mature kallikrein

Human tissue prokallikrein is the enzymatically inactive zymogen of a serin e proteinase involved in the liberation of vasoactive kinin peptides, and i t is supposed that an impaired prokallikrein-to-kallikrein conversion is cl osely related to certain hypertensive and inflammatory disorders. Progress in understanding the biological role of the proenzyme has been limited by t he absence of an accurate assay for the kallikrein precursor. We describe a sandwich enzyme-linked immunosorbent assay to measure human tissue prokall ikrein using monospecific anti-peptide antibodies raised against propeptide derivatives. This method could detect a minimum concentration of 60 pg/ml prokallikrein and displayed no cross-reactivity or interference with mature tissue kallikrein. The intra- and inter-assay precision varied from 8-15%, respectively, indicating a reasonable reproducibility of the method. The l evel of prokallikrein was defined in different human urine samples, and the corresponding dilution curves showed good linearity. The mean recovery of added zymogen was 104%. Prokallikrein immunoassay is the first reported too l for the direct and sensitive quantification of the precursor of tissue ka llikrein and should facilitate the precise determination of prokallikrein l evels in a variety of biological specimen.