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

SKALP/elafin is an epithelial proteinase inhibitor with antimicrobial properties that is not normally expressed in human epidermis, but is induced under inflammatory conditions and in some types of skin cancer. SKALP is a member of the recently described trappin gene family, which encodes a new class of proteins, characterized by a four-disulphide core and a transglutaminase substrate domain. Polyclonal antisera against SKALP have been shown to be useful for monitoring disease activity in psoriasis and tumour differentiation in squamous cell carcinoma. We developed ten different mouse monoclonal antibodies (mAbs) against synthetic peptides corresponding to a hexapeptide epitope in the transglutaminase substrate domain and three mAbs recognizing an epitope in the proteinase-inhibiting domain. The antibodies could be used with high specificity by immunohistochemistry on formalin-fixed tissue, by affinity chromatography, by Western blotting, and by enzyme-linked immunoadsorbent assay (ELISA) for the detection of SKALP/ elafin. These antibodies have several advantages over existing polyclonal antisera, such as a defined epitope, the detection of full-length SKALP/elafin and unlimited supply. An antibody against the hexapeptide epitope, which is common to all known human, simian, bovine and swine trappin family members, was used to immunolocalize 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.