ALLERGEN SPECIFICITY OF SKIN-INFILTRATING T-CELLS IS NOT RESTRICTED TO A TYPE-2 CYTOKINE PATTERN IN CHRONIC LESIONS OF ATOPIC-DERMATITIS

The majority of allergen-specific T cells derived from inhalant allerg en patch test lesions in patients with atopic dermatitis were previous ly found to produce a restricted type-2 cytokine pattern, Recent Studi es, however, have revealed that in chronic eczematous skin lesions of patients with atopic dermatitis, expression of the type-1 cytokine int erferon-gamma predominates, To evaluate cytokine production by allerge n-specific T cells in chronic atopic dermatitis, we established house dust mite (Dermatophagoides pteronyssinus)-specific T-cell clones from the dermis of chronic skin lesions of sensitized adult patients with atopic dermatitis. Frequencies of skin-derived T cells proliferating i n the presence of Dermatophagoides pteronyssinus were between one in 1 38 and one in 4255, indicating that only a minority of skin-infiltrati ng T cells are allergen specific. When these cells were analyzed for t heir capacity to produce interferon-gamma, the majority (71%) of these cells were found to express interferon-gamma mRNA and to secrete inte rferon-gamma protein, either alone or in combination with interleukin- 4. Phenotypic analysis revealed that 15% of skin-infiltrating allergen -specific T cells were CD8(+). No selection of V beta elements was det ected in Dermatophagoides pteronyssinus-specific T-cell clones. These studies demonstrate that allergen specificity of skin-infiltrating T c ells is not restricted to a type-1 cytokine pattern in lesional atopic dermatitis, The notion that the majority of allergen-specific, skin-i nfiltrating T cells are capable of producing interferon-gamma further Supports the concept that interferon-gamma expression has major pathog enetic relevance for the chronic phase of atopic dermatitis.