Keratin expression in lesional, marginal and uninvolved psoriatic epidermis was analysed by one- and two-dimensional gel electrophoresis and immunoblotting. Keratins K1, K5, K6, K10, K14, and K16 were identified in lesional epidermis. Keratins K6 and K16 were found in all epidermis probes of uninvolved skin, but never occurred in normal epidermis of control skin samples. By means of laser-densitometric evaluation of one-dimensional gels a downregulation of K1 and K10 and an upregulation of K6 and K16 was found in psoriatic epidermis. Unexpectedly, the level of K5 was considerably lower and the level of K14 considerably higher in lesional skin than in normal epidermis. These results demonstrate that not only basal keratinocytes in lesional epidermis but also suprabasal keratinocytes in uninvolved psoriatic epidermis express an altered differentiation pattern. The latter phenomenon could be very important in understanding the development of the so-called "Köbner effect" in psoriatic epidermis.

Matrix metalloproteinases (MMP) are involved in remodelling of the extracellular matrix (ECM) proteins suggesting that they play an important role in inflammatory process, in tumour invasion and metastasis. We examined immunohistochemically 330 cases of different skin disorders with the monoclonal antibody against MMP 11, stromelysin-3 (ST-3) protein. We found a positive immunoreactivity in fibroblasts surrounding malignant epithelial tumour cells in 63 of 125 cases (50.4%) of basal cell carcinomas, in four of 25 (16%) squamous cell carcinomas, whereas the tumour cells themselves were negative. Furthermore, the ST-3 protein could be detected in 23 of 40 cases (57.5%) of dermatofibroma, in two of five cases (40%) of atypical fibroxanthoma, in one of eight cases (12.5%) of dermatofibrosarcoma protuberans and, locally, in one of 10 cases (10%) of malignant fibrous histiocytoma. It was not present in the following skin lesions: keratoakanthomas (n = 12), Bowen's disease (n = 10), malignant melanoma (n = 12), melanocytic nevi (n = 28) and Kaposi's sarcomas (n = 25). In eczema (n = 10), psoriasis (n = 10) and virus-induced tissues (i.e. condylomata acuminata, n = 10) we did not observe an expression of ST-3 protein. We conclude first that ST-3 protein is a fibroblastic factor expressed in stromal cells adjacent to carcinoma cells; second, that ST-3 protein seems to be associated with benign fibroblastic tumours; and third, that it does not play a role in eczema, psoriasis or virus-induced skin lesions.

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Metallic orthopaedics implants are composed of elements that are known to be skin sensitizers in the general population. In this study, we analyzed the cells of perivascular infiltration in the tissue adjacent to titanium (n = 23) and steel (n = 8) implants after explantation of the metals by immunohistochemical methods. The following panel of monoclonal antibodies were used as parameters: CD 1a (Langerhans cells), CD 4 (T-helper cells), CD 8 (T-suppressor cells), CD 11c (monocytes and macrophages), CD 45 RO (memory cells), CD 45 RA (naive cells), eosinophil cationic proteins (ECP), neutrophil elastase, and HLA-DR. The number of perivascular total cells did not differ significantly. All cells were identified in both metal subgroups, but a statistical difference was not seen in the above-mentioned parameters. We conclude that sensitization to metals is possible in the tissue adjacent to steel and titanium implants, because all cells which play an important role in allergic delayed-type hypersensitivity (type IV) reactions are present. This phenomenon may be called a 'pre-sensitization' phase, because no sensitization or allergic reactions were seen in our cases. Second, in the present study, a statistical difference was not seen in the number of infiltrate cells in the tissue adjacent to steel compared with titanium implants.