Abstract: Objectives To determine the CD68⁺ and CDla⁺ cells within normal human epidermis and the relationship of each other. Methods Skin samples from 8 healthy subjects were collected from 6 regions:face, trunk, proximal limb, distal limb, palm and sole. Epidermal sheets and skin sections of these samples were stained with CDla and CD68 monoclonal antibodies by an ABC immunoperoxidase and a double-labelled immunofluorescence procedure. The density and location of these stained cells in the epidermis were determined. Results The majority of CDla⁺ dendritic cells were located at the mid-epidermis in the skin sections, while CD68 positive cells were less likely to be dendritic in morphology, and were located mainly in the midand lower epidermis. In the epidermal sheets, the densities of CD1a and CD68 positive cells in the palm and sole were low:ranging from 184 to 252 per mm² and from 232 to 310 per mm², respectively. There were much more CD1a and CD68 positive cells in the face, trunk and limb:the densities ranged from 530 to 809 per mm² and from 524 to 637 per mm², respectively. The CD1a and CD68 double-labelled dendritic cells were mainly located in the mid-epidermis. The linear density of double-labelled positive cells accounted for less than half of that of CDla or CD68 positive cells (28.6%～49.8%). Conclusions There are three types of cells with different markers, CD1a⁺CD68⁺,CD1a⁺CD68^- and CD1a^-CD68⁺ in normal human epidermis.

Key words: Epidermis, Langerhans cells, Antigens, CD