Development and application of monoclonal antibodies against SKALP/elafin and other trappin family members

SKALP/elafin is an epithelial proteinase inhibitor with antimicrobial prope rties that is not normally expressed in human epidermis, but is induced und er inflammatory conditions and in some types of skin cancer. SKALP is a mem ber of the recently described trappin gene family, which encodes a new clas s of proteins, characterized by a four-disulphide core and a transglutamina se substrate domain. Polyclonal antisera against SKALP have been shown to b e useful for monitoring disease activity in psoriasis and tumour differenti ation in squamous cell carcinoma. We developed ten different mouse monoclon al antibodies (mAbs) against synthetic peptides corresponding to a hexapept ide epitope in the transglutaminase substrate domain and three mAbs recogni zing an epitope in the proteinase-inhibiting domain. The antibodies could b e used with high specificity by immunohistochemistry on formalin-fixed tiss ue, by affinity chromatography, by Western blotting, and by enzyme-linked i mmunoadsorbent assay (ELISA) for the detection of SKALP/ elafin. These anti bodies have several advantages over existing polyclonal antisera, such as a defined epitope, the detection of full-length SKALP/elafin and unlimited s upply. An antibody against the hexapeptide epitope, which is common to all known human, simian, bovine and swine trappin family members, was used to i mmunolocalize bovine trappins expressed in trachea, that have recently been discovered. These mAbs will serve as important new tools to measure SKALP/ elafin and trappin family members in research and diagnostics.