IN-VIVO CYTOKINE PROFILES IN ALLERGIC AND IRRITANT CONTACT-DERMATITIS

Local cytokine profiles in skin biopsies from allergic and irritant patch test reactions were determined by in vivo immunohistochemistry to differentiate between these 2 clinically identical afflictions especially at the time of final reading in diagnostic patch testing. Biopsies were taken from established allergic persons after specific allergic patch tests to epoxy resin (1%), and formaldehyde (1%) and from non-allergic individuals with irritant patch tests to sodium lauryl sulfate (10%) and formaldehyde (8%). At 72 h after application of the agents, significantly enhanced frequencies of dermal infiltrating cells, producing IL-1 alpha, TNF-alpha, 1L-2, and IFN-gamma per 100 infiltrating cells in the dermis, were observed in allergic as well as irritant patch test reactions, as compared to normal skin. Significantly higher frequencies of IL-1 alpha-producing cells were observed in biopsies from epoxy resin (1%) allergen-affected and sodium lauryl sulfate (10%) irritant-affected skin as compared to formaldehyde (1%) allergen-affected skin. In addition, significantly higher frequencies of TNF-alpha-producing cells were observed in epoxy resin allergen-affected skin as compared to formaldehyde (1%) allergen-affected and formaldehyde (8%) irritant affected skin. The allergic and irritant patch test reactions showed similar levels of expression of the Th1 cytokines 1L-2 and IFN-gamma in the dermis, confirmed by probe based detection of 1L-2 mRNA and IFN-gamma mRNA. In conclusion, the. described similarity shows that allergens and irritants can induce the same profile of IL-1 alpha, TNF-alpha, 1L-2, and IFN-gamma production, resulting in the near impossibility of discriminating between allergic and irritant contact dermatitis at the time of patch test reading.