CD4+ T cell depletion changes the cytokine environment from a TH1/TH2 response to a TC17-like response in a murine model of atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disease often associated with co-morbidities including allergic hypersensitivity. We have studied induced AD-like disease in NC/Nga mice using the hapten FITC. Following FITC-treatment the NC/Nga mice develop AD-like skin lesions in regard to the histopathological and immunological changes. Consistent with AD in humans the number of CD4(+) T cells within the blood and draining lymph nodes increases considerably. To evaluate the contribution of T-H cells on disease development we examined the effect of CD4 depletion. Following CD4 depletion the mice still develop AD-like skin lesions characterized by e.g. increased epidermal proliferation, hyperkeratosis and cellular infiltrate, however, the underlying immunological mechanisms change. CD4 depletion results in increased IL-17A and IL-22 production, which traditionally are associated with T(H)17 cells. Using confocal microscopy, we demonstrate that epidermal CD8(+) cells are positive for IL-17A, indicating that these cells are T(C)17 cells, the cytotoxic T cell counterpart to T(H)17 cells. In conclusion, we show that NC/Nga mice develop AD-like disease following CD4 depletion. This is mirrored by an increased production of IL-17A, which we suggest are produced by T(C)17 cells. These findings support that CD8(+) T cells can play a role in AD. (C) 2011 Elsevier B.V. All rights reserved.