The presence of professional antigen-presenting cells in tumours can influence their further spreading. Location of cells exhibiting a specific marker of Langerhans cells--Langerin, and the 175 kD mannose receptor as a marker of dendritic cells of non-Langerhans type and macrophages, was studied using double staining in the normal human epidermis and in basal cell carcinomas. The Langerin-positive cells strictly colonized the epidermis and no cells were found in the dermis, where 175 kD mannose

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... receptor-exhibiting cells were present. Very rare elements in the epidermal/dermal interface were positive for both markers. A low incidence of Langerin-positive cells was found in tumours and 1/3 of studied carcinomas were even Langerhans cell-free. The extraepithelial presence of Langerin-positive cells forming contacts with dendrite-like protrusions of 175 kD mannose receptor-exhibiting cells was found in connective tissue surrounding the tumour epithelium and indicates possible cooperation of both elements.