COMPARATIVE-ANALYSIS OF THE FREQUENCY OF HOUSE-DUST MITE SPECIFIC ANDNONSPECIFIC TH1 AND TH2 CELLS IN SKIN-LESIONS AND PERIPHERAL-BLOOD OFPATIENTS WITH ATOPIC-DERMATITIS

Until recently it was believed that the T cell response of atopic derm atitis patients challenged with inhalant allergens originates almost e xclusively and specifically from Th2 cells capable of secreting an abu ndance of interleukin (IL)-4 while producing no interferon (IFN)-gamma . To reevaluate this concept in a large cohort of atopic dermatitis pa tients we established 177 CD4(+) T cell clones (45 of which showed spe cificity for house dust mite antigen) from the peripheral blood (n=76) , naturally occurring skin lesions (n=40), and allergen-exposed skin ( n=61) of different patients. These clones were examined for their capa city to secrete IL-4 and IFN-gamma upon mitogenic stimulation. Moreove r, 20 of these T cell clones were investigated for the synthesis of tr anscripts for IL-5, another Th cytokine. Our results indicate that the majority (52-100%) of allergen-specific T cells in both skin and bloo d of atopic individuals failed to exhibit a restricted cytokine secret ion pattern and thus were classified as Th0 cells. House dust mite ant igen specific T cells displaying a restricted secretion pattern (n=16) were either of the Th1 or the Th2 type. Specific Th2 cells, however, were found almost exclusively in allergen patch test reactions, indica ting that the Th2 differentiation pathway is seen preferentially in al lergen-exposed skin. The cytokine secretion profile of T cell clones o btained from naturally occurring skin lesions showed similarity to tho se of patch test lesion, suggesting that the patch test represents a u seful model to investigate the pathogenesis of atopic dermatitis.