Increased circulating skin-homing cutaneous lymphocyte-associated antigen (CLA)+ type 2 cytokine-producing cells, and decreased CLA+ type 1 cytokine-producing cells in atopic dermatitis.

Skin-homing T cells are characterized by expression of cutaneous lymphocyte-associated antigen (CLA). Few data are available on the frequency of circulating CLA+ cytokine-producing T cells in atopic dermatitis (AD) patients. We aimed to investigate cytokine synthesis capability vs. CLA expression in phorbol myristate acetate and ionomycin-stimulated, secretion-inhibited peripheral blood T cells of AD patients compared with healthy subjects and psoriatic patients. Multiparameter flow cytometry was used. The expression of CLA among CD4+ T cells was significantly elevated in AD patients compared with healthy subjects and psoriatic patients, whereas there was no significant difference between each group in CLA expression among CD8+ T cells. The frequency of interleukin (IL)-4- and IL-13-producing cells in AD patients was significantly higher than in healthy subjects (in both CD4+ and CD8+ T-cell subsets) and psoriatic patients (in CD4+ T cells). In contrast, the frequency of interferon (IFN)-gamma-producing cells was significantly reduced in AD patients, among both CD4+ and CD8+ T cells, compared with healthy subjects and psoriatic patients. Moreover, in AD patients, the frequency of IL-4- and IL-13-producing cells was remarkably increased among the CLA+ subset (in both CD4+ and CD8+ T cells), whereas the frequency of IFN-gamma-producing cells was decreased in the CLA+ subset (in CD4+, but not in CD8+ T cells). These results provide evidence for the expansion of skin-homing type 2 cytokine-secreting T cells, associated with a reduction in skin-homing type 1 cytokine-producing T cells, in peripheral blood of AD patients.