IN-VIVO EXPRESSION OF IL-12 AND IL-13 IN ATOPIC-DERMATITIS

Previous studies in atopic dermatitis (AD) have shown that acute and c hronic skin lesions are associated with a TH2-type profile of cytokine expression. IL-12 and IL-13 are recently described cytokines, which p ossess TH1- and TH2- like actions, respectively. We have used the tech nique of in situ hybridization to examine the expression of IL-12 and IL-13 messenger RNA in skin biopsy specimens of acute and chronic skin lesions and uninvolved skin from patients with AD. When compared with normal control skin, the acute and chronic skin lesions and unaffecte d skirt from patients with AD had significantly greater numbers of cel ls that were positive for IL-13 mRNA (p < 0.05). Acute AD skin lesions expressed a higher number of positive cells than those observed in ch ronic AD skin lesions (p < 0.05) or psoriasis skin lesions (p < 0.05) There was a significant increase in the numbers of IL-12 mRNA-positive cells in chronic skin lesions compared with acute lesions and uninvol ved skin from patients with AD (p < 0.05). These data demonstrate that acute AD skin lesions are associated with an increased expression of IL-13 mRNA. In contrast, the relative increase in IL-12 mRNA in chroni c AD skin lesions suggests a possible role for IL-12-producing cells i n modulating chronic inflammation.