Potential role of interleukin-10-secreting regulatory T cells in allergy and asthma

Allergic diseases — such as allergic rhinitis, asthma and atopic dermatitis — have diverse clinical features, but they have analogous immunological characteristics. Patients show upregulation of allergen-specific CD4+ T helper 2 (TH2) cells and allergen-specific IgE.Strategies to promote long-term relief from the symptoms of allergic disease aim to inhibit allergen-specific TH2-cytokine responses.Recently, several T-cell populations with the capacity to regulate immune responses have been described. These are known as regulatory T cells, and evidence is emerging that the function of regulatory T cells might be impaired in some allergic diseases.Interleukin-10 (IL-10) is an anti-inflammatory cytokine, and it is produced by some populations of regulatory T cells (called IL-10-secreting regulatory T cells), as well as by antigen-presenting cells. It is an attractive candidate for the treatment of allergic asthma.Some existing therapies for allergic diseases — both non-specific therapies, such as treatment with glucocorticoids, and specific therapies, such as allergen-desensitization immunotherapy — might function, at least in part, to promote the function of IL-10-secreting regulatory T cells.Novel approaches that build on these observations are discussed, both experimental and those being tested in clinical trials.