Immunohistochemical distribution of cutaneous fatty acid-binding protein in human skin.

Cutaneous fatty acid-binding protein (C-FABP) has been newly discovered from rat skin. The immunohistochemical study revealed that C-FABP is strongly expressed in rat epidermis. Recently, a highly homologous protein to rat C-FABP was found in psoriatic epidermis, which is termed psoriasis-associated fatty acid-binding protein (PA-FABP). In the present study, we investigated the expression of PA-FABP in normal and pathological human skin using immunohistochemical techniques. In normal skin, PA-FABP was expressed in basal and prickle cell layers, and more strongly in the granular cell layer. The expression pattern of PA-FABP was similar to that of C-FABP in rat skin. In psoriatic skin, PA-FABP was expressed in suprabasal layers and more strongly in more differentiated keratinocytes. In squamous cell carcinoma, PA-FABP showed very strong expression in squamous nests. These results indicate that PA-FABP is a human homologue of C-FABP. Moreover, it is suggested that C-FABP has important roles in the transport and metabolism of fatty acids in epidermis and that altered lipid metabolism may affect the proliferation and/or differentiation of keratinocyte.