Lectin binding patterns and monoclonal antibodies to epidermal antigens in tumours of the skin

Monoclonal antibodies to epidermal antigens and cell surface carbohydrate markers, as defined by lectin binding, were used to analyze the cells in squamous and basal cell carcinomas of the skin (SCC and BCC). The cells in BCC failed to stain with the lectin peanut agglutinin (PNA), which stains surface carbohydrates of cells in the stratum spinosum and stratum granulosum layers of normal epidermis, confirming histological observations that the cells in BCC are incapable of differentiation beyond the basal cell stage. Conversely, the central cells in SCC did react with PNA, suggesting that they can differentiate to a stage equivalent to the stratum spinosum of epidermis. The zone immediately surrounding BCC differed from that around SCC in lectin binding and staining with antisera to laminin and fibronectin, an observation which could be connected with the failure to metastasize. It was of interest that histologically normal skin immediately adjacent to and overlying these tumours showed marked changes in reaction with markers of normal epidermis. The outer layers of this epidermis showed aberrant retention of the lower molecular weight cytokeratins marked by the monoclonal antibodies LMM2 and LMM3, and occasional strong staining of individual cells by the stratum granulosum-reactive LMM1. These changes appear to be indicative of a 'premalignant' state in these cells and the monoclonal antibodies are thus potentially useful reagents for early detection of skin malignancies.