INTERFERON-GAMMA PROMOTES EXAGGERATED CYTOKINE PRODUCTION IN KERATINOCYTES CULTURED FROM PATIENTS WITH ATOPIC-DERMATITIS

Recent studies suggest that skin keratinocytes from patients with atop ic dermatitis (AD) and nonatopic subjects differ in their intrinsic ab ility to respond to proinflammatory stimuli. In this study keratinocyt e cultures established from the normal-looking skin of six adult patie nts with AD and six healthy, nonatopic control subjects were compared in their response to interferon-gamma, a potent proinflammatory lympho kine whose expression is increased in chronic AD lesions. Basal expres sion of IFN-gamma receptor as well as IFN-gamma-induced membrane expre ssion of HLA-DR and intercellular adhesion molecule (ICAM)-1 were eval uated by flow cytometry. Keratinocyte release of IL-1 alpha, IL-1 rece ptor antagonist (IL-1ra), granulocyte-macrophage colony stimulating fa ctor (GM-CSF), and tumor necrosis factor (TNF)-alpha were measured by ELISA on culture supernatants after treatment with IFN-gamma or medium alone. Expression of membrane IFN-gamma receptor was similar in kerat inocytes cultured from nonatopic subjects and subjects with AD. IFN-ga mma (10 to 500 U/ml) induced comparable levels of membrane HLA-DR and ICAM-1 in both groups of keratinocytes. In contrast, spontaneous relea se of IL-1 alpha, IL-1ra, GM-CSF, and TNF-alpha were measured by ELISA on culture supernatants after treatment with IFN-gamma or medium alon e. Expression of membrane IFN-gamma receptor was similar in keratinocy tes cultured from nonatopic subjects and subjects with AD. IFN-gamma ( 10 to 500 U/ml) induced comparable levels of membrane HLA-DR and ICAM- 1 in both groups of keratinocytes. In contrast, spontaneous release of IL-1 alpha, IL-1ra, GM-CSF, and TNF-alpha was increased in the supern atants of unstimulated keratinocytes from control subjects, with IL-1r a and GM-CSF reaching statistically significant difference. Moreover, IFN-gamma-induced release of all the cytokines tested was much higher for keratinocytes from patients with AD, but the IL-1ra/IL-1 alpha rat io for the two groups of keratinocytes was not substantially different , either basally or after IFN-gamma stimulation. The results indicate that keratinocytes from patients with AD are hyperresponsive to IFN-ga mma in terms of cytokine release.