Regulatory T cells as a target for induction of immune tolerance in allergy

PURPOSE OF REVIEW: Reduced activity of regulatory T cells has recently been described in several diseases, including allergy. This concept of an alteration in the balance between the suppression and activation of harmful T helper type 2 immunity in allergy has important potential implications for strategies to prevent and control disease. RECENT FINDINGS: The past year has seen several important advances in analysing the determinants of this balance and models for inducing tolerance through regulatory T cells, including several different subtypes. These include the recognition that although T helper type 2 responses drive atopic sensitization, the expression of disease involves additional factors, and of a potential role for regulatory T cells in the development of neonatal tolerance. In addition to CD4CD25 regulatory T cells, experimental protocols for the induction of IL-10-producing, transforming growth factor beta and T helper type 1 regulatory T cells have been described in mouse models of airway disease. IL-6 and co-stimulation have been identified as potential determinants of the balance between the suppression and activation of allergic responses. SUMMARY: Different strategies for inducing regulatory T cells in animal models of allergic inflammation and an improved understanding of the factors accentuating or reducing suppression have identified important questions for future translational research.