A study revealed that DCs from children with allergic rhinitis can be impaired in their capacity toproduce IL-10. Interestingly, allergen-specific IL-10-secreting Tr1 cells are highly represented in healthy individuals in comparison with allergen-specific IL-4-secreting Th2 cells, suggesting that regulatory T cells are predominant during natural immune responses to environmental allergens in nonatopic donors. Regulatory T lymphocytes can control an established allergic response via distinct mechanisms: IL-10 and TGF-β decrease IgE production and enhance IgG4 and IgA production, respectively.