Enzyme-linked immunoabsorbent assay for detection of human serine protease corin in blood

Background: Corin is a tissue type II transmembrane protein that converts pro-atrial natriuretic peptides and pro-brain natriuretic peptide to their active forms. Despite their protecting effect, high levels of these peptides indicate a bad prognosis. One of the possible explanations to this paradox is reduced cleavage due to low corin levels. The purpose of this study was to develop an assay to detect blood levels of corin. Methods: ELISA was developed using rat monoclonal antibody to recombinant human corin as capture antibody, and biotinylated goat anti-human corin as detection antibody. Results: Based on known corin concentration as standards, the ideal capture antibody concentration was 500 ng/ml, and 200 ng/ml for detection antibody. The coefficient of variation was 5.7% for inter-assay and 3.9% for intra-assay precision. Corin levels were stable when stored at room temperature for 1 day, for 3 days at 4 °C or up to 1 year in - 35 °C. Human serum corin levels were reproducibly measured in individuals and found to range from 296 to 2590 pg/ml. Conclusions: The immunoabsorbent assay developed in this study can accurately and reliably determine human serum corin levels, and is suitable for simple screening of corin in clinical practice.