ABSTRACT
To understand the role of Transglutaminase K(TGase K) in skin diseases, the expression of TGase K protein was studied in hyperkeratotic inflammatory skin diseases, and in several different kinds of benign and malignant skin tumors. Immunohistochemistry was used to detect the TGase K protein with a new anti-human TGase K polyclonal antibody. This antibody showed the same immuno- histochemical staining pattern as in previously published immunofluorescence data with the exception that the immunohistochemical stain showed a slightly weaker stain in the granular layer. However, the staining intensity was decreased in psoriasis, which is opposite for results obtained with the widely used TGase K monoclonal antibody B.C1. In other hyperkeratotic inflammatory skin diseases, like pityriasis rubra pilaria, lichen planus, and pityriasis rosea, the staining patterns were similar while the staining intensity was decreased, compared to normal epidermis. Squamous cell carcinoma showed a diffuse staining pattern in tumor cells with a small intensity increase in well differentiated tumor cells. However, in actinic keratosis and Bowen's disease, which are thought to be precursors of squamous cell carcinoma, the staining intensity was weak. The tumor cells of basal cell carcinoma, malignant melanoma, and seborrheic keratosis showed a weak staining intensity.