EXPRESSION OF ANNEXIN-I IN FRESHLY ISOLATED HUMAN EPIDERMAL-CELLS ANDIN CULTURED KERATINOCYTES

Annexin I belongs to a newly characterized family of intracellular pro teins involved in the regulation of the production of inflammatory lip id mediators such as prostaglandins and leucotrienes. Annexin I (named p35, lipocortin I or calpactin TT) was initially described as a prote in inducible by glucocorticoids. In the skin, the role of annexins has still not been elucidated. In the study reported here,ve investigated the expression of annexin I both in freshly isolated epidermal cells and in cultured keratinocytes using immunofluorescence, FACS analysis and immunoblotting techniques. Using epidermal cells freshly isolated from normal skin, annexin T was detected by double immunostaining main ly in basal and suprabasal keratinocytes. Langerhans cells isolated fr om FicolI gradient were faintly stained compared with keratinocytes. A nnexin I was also highly expressed in keratinocytes maintained in cult ure in a serum-free medium without hydrocortisone. By confocal microsc opy, annexin I was shown to be mainly localized in the cytoplasm of th e cells. The protein was characterized by Western blot and immunopreci pitation as a 35-kDa protein in freshly isolated epidermal cells and c ultured keratinocytes. Results from in vivo studies confirmed the pres ence of annexin I in the basal and suprabasal layers of normal human s kin with modified reactivity patterns in hyperproliferative lesions.