ASSOCIATION BETWEEN EXPRESSION OF STRATUM-CORNEUM CHYMOTRYPTIC ENZYMEAND PATHOLOGICAL KERATINIZATION IN HUMAN ORAL-MUCOSA

Stratum corneum chymotryptic enzyme (SCCE) may function in the degrada tion of intercellular cohesive structures in the stratum corneum prece ding desquamation, Previous results have suggested that SCCE may be sp ecifically expressed in squamous epithelia undergoing terminal differe ntiation and keratinization. The aim of the present work was to furthe r elucidate the association between SCCE expression and terminal diffe rentiation in squamous epithelia. Using immunohistochemical methods, w e have examined the expression of SCCE in two diseases of human oral m ucosa, which produce a pathological keratinization of the epithelium a t sites which are normally non-keratinized, Affinity-purified polyclon al rabbit antibodies raised against recombinant SCCE and monoclonal an tibodies against the differentiation-specific keratins nos. 10 and 13 were used on formaldehyde-fixed and paraffin-embedded biopsies. Wherea s there was essentially no expression of SCCE in normal, non-keratiniz ed buccal mucosa, there was a strong expression in suprabasal cells in orthokeratotic and parakeratotic areas of the lesions of oral lichen planus (an inflammatory disease) and benign oral keratosis (a non-infl ammatory disease). There was a close association between the expressio n of SCCE and keratin no, 10, i.e, a keratin which is specifically exp ressed in cornifying squamous epithelia. The results suggest that SCCE expression may be a true marker of terminal differentiation in squamo us epithelia and give further evidence for a role of SCCE in the forma tion and/or turnover of the stratum corneum.