IL-10 secretion of allergen-specific skin-derived T cells correlates positively with that of the Th2 cytokines IL-4 and IL-5.

In atopic individuals, allergen-specific CD4+ T lymphocytes often belong to the T-helper 2 (Th2) subset as they secrete the marker cytokines interleukin-4 (IL-4) and IL-5 but not interferon-gamma (INF-gamma). IL-10 is a cytokine the production of which, in the mouse system has been described to be restricted to the Th2 subset, but in the human was found to be produced by both Th1 and Th2 T cell clones (TCC). We have recently shown that house dust mite antigen (Dermatophagoides pteronyssinus)-specific TCC isolated from skin of patients with atopic dermatitis have a more polarized Th2 cytokine production profile than TCC obtained from the peripheral blood of these patients. In this study, we report that skin-derived TCC secrete more IL-10, IL-4 and IL-5, than TCC isolated from the blood of the same individual (p < 0.05). The difference was more significant with specific TCC than with non-specific TCC. Furthermore, there was a positive correlation between the production of IL-10 and that of IL-4 and IL-5, respectively. In addition, the amount of IL-4 and IL-5 secreted by specific TCC from the skin correlated positively. These results were confirmed by the detection of mRNA by PCR. Finally, our data confirm that in human blood-derived TCC IL-10 secretion is not related to a particular cytokine production profile. We suggest that the skin of AD provides an unique environment for the development of aTh2-like secretion pattern not only with respect to IL-4 and IL-5 but also regarding IL-10.