ABSTRACT
The normal indigenous cells of the human dermis until newly were dismissed as spindle-shaped fibroblasts. However, meticulous frozen sections of human skin using oxidative enzyme methods have revealed a dermal terra nova populated by well-differentiated cells having highly dendritic morphology. Dendritic cells are also aggregated in the dermal perivascular adventitia, particularly around small vessels of the superficial dermal vascular plexus. Based on immunocytochemical studies, the bone marrow is considered the presumptive origin of most immunocompetent dendritic cells. Immunocompetent dermal dendrocytes are probably functionally related to other immunocompetent dendritic cells in both lymphoid and nonlymphoid tissues. Ultrastructural studies of the dermis have confirmed the dendritic cell morphology. Some dermal dendrocytes are positive for alpha naphthyl butyrate esterase, β-glucuronidase, and acid phosphatase. Dermal dendrocytes have been shown to express tumor necrosis factor alpha, intercellular adhesion molecule-1, interferon gamma, and interleukin-8 in psoriatic lesions but with negative or minimal expression in normal skin.
