Abstract: A monoclonal antibody by which medullasin that is a kind of serine proteases existing in granulocytes, production process thereof and an immunoassay of human medullasin using the antibody are disclosed. The monoclonal antibody specifically recognizes human medullasin. The process for producing the anti-human medullasin antibody comprises culturing hybridomas prepared by cell fusion between antibody-producing cells recovered from an animal immunized with human medullasin and myeloma cells, and recovering anti-human medullasin monoclonal antibody which specifically recognizes human medullasin from the culture in which the hybridomas are cultured. The immunoassay utilizes the anti-human medullasin antibody.

Abstract: The present invention offers the serine protease exhibiting a biological activity which a polypeptide having an amino acid sequence shown in FIG. 1 shows, the serine protease precursor where a cleavable peptide or signal peptide connects with the N-terminal of the said serine protease, and the gene encoding them. The serine protease being useful in medical treatment fields can be manufactured in large quantities by the present invention.Moreover, the present invention offers the DNA sequence coding a transcription controlling region contained in the chromosomal gene of the serine protease of a human myeloid cell. This sequence is the transcription controlling region being necessary for the gene expression being specific to a human leukocyte or erythrocyte.