Similarly, transfer of CD4+ T cells overexpressing IL-10 to the lungs was sufficient to reverse airway inflammation and hyperresponsiveness in a similar model.109 Induction of IL-10 production by CD4+ T cells was also essential for the efficacy of peptide immunotherapy in a murine model of cat allergen-driven airway inflammation110 and is associated with effective immunotherapy with grass pollen allergens in patients with seasonal allergic rhinitis (SAR),111,112 highlighting the potential for T helper cell-derived IL-10 to limit pathogenic immune responses to aeroallergens. This evidence concerns the gene IL10 and seasonal allergic rhinitis.