Figure. 1.

Control of allergic airway disease by regulatory T cells. Allergic airway disease is caused by inappropriate Th2-driven immune responses to “harmless” antigens, or allergens, in the environment. CD4⁺CD25⁺ and IL-10–producing T reg cells can regulate allergic sensitization in vivo through inhibitory effects on Th2 cells or on dendritic cells (DCs) in the lung. T reg cells can also induce the production of the immunosuppressive cytokine IL-10 by host lung T cells (not shown). In turn, DCs can produce immunomodulatory cytokines such as IL-6, which has been shown to inhibit CD4⁺CD25⁺+ T reg cell function, and IL-10, which has been shown to induce IL-10–producing T reg cells.