ANALYSIS OF THE CYTOKINE PATTERN EXPRESSED IN-SITU IN INHALANT ALLERGEN PATCH TEST REACTIONS OF ATOPIC-DERMATITIS PATIENTS

In the present study, we examined the cytokine pattern expressed in si tu during the development of eczematous reactions that had been provok ed in atopic dermatitis patients by patch testing with house dust mite allergen, In 24-h house dust mite allergen patch test reactions, expr ession of interleukin (IL)-4 mRNA and IL-2 mRNA increased, but interfe ron (IFN)-gamma mRNA did not, as compared with control skin, In 48-h i nhalant allergen patch test reactions, however, IFN-gamma mRNA and IL- 2 mRNA expression were increased above levels observed in control skin , whereas IL-4 mRNA expression was decreased below background levels, These data demonstrate that a switch from a Th-2-like to a Th-1-like c ytokine response occurs in inhalant allergen patch tests of atopic der matitis patients, This biphasic pattern was specific to inhalant aller gen patch test reactions, as it was not observed in irritant reactions in the same patient, IFN-gamma production by T cells may be induced b y the cytokine IL-12. In the present study, upregulation of IFN-gamma mRNA expression in inhalant allergen patch test reactions was preceded by an increased expression of the p35 subunit of IL-12 mRNA. These ob servations suggest that increased IL-12 expression may contribute to t he observed switch of the in situ cytokine secretion pattern. Further studies are necessary to determine whether a similar biphasic pattern of cytokine expression is also operative in the initiation phase of at opic eczema.