Epidermal antigens in cutaneous dysplasia and neoplasia in hairless mice

Abstract

Tissue-specific antigen deletion is a feature of experimental and human tumours, including squamous cell carcinomas in man and mouse. The patterns of epidermal antigens were correlated with the histology of proliferative skin lesions induced in hairless mice, with u.v. light (wavelength 2800-3200 A and as a comparison, 3-methylcholanthrene. Epidermal hyperplasia occurred in 3-8 wk., dysplastic changes in 2-4 mth. and squamous cell carcinomas from 4 mth. onwards. Antigenic changes in the treated skins were assessed by the indirect immunofluorescent method, using sera from patients with (a) pemphigus vulgaris, which stains the intercellular areas and cell membranes of normal epidermal cells, and (b) bullous pemphigoid, which stains the basement membrane zone of normal epidermis. Antigen deletion was not detected in hyperplastic lesions. Early dysplastic lesions showed focal loss of epidermal cell membrane staining in the 2 or 3 layers of cells immediately above the basement membrane zone; the staining of the associated basement membrane zone remained normal. With malignant change and invasion of the dermis, loss of epidermal cell membrane antigenicity was almost complete, except in isolated areas where the neoplastic cells had differentiated towards more typical squames. With invasion, the basement membrane zone staining became irregular, granular, or completely lost, particularly in regions where tumour cells were deep in the dermis. It was suggested that loss of epidermal cell membrane antigens in dysplastic lesions is an index of de-differentiation towards malignancy. Loss of basement membrane zone antigenicity is associated with tumour invasion into the dermis.