Consistent with this, our data suggest that defective IL-21+ CD4+ T cells might contribute to allergy in Dock8 KO mice, and that supplementation with IL-21 reduces airway inflammatory infiltration, as well as the number of serum IgE and IgE-producing B cells, in the OVA-induced allergic asthma model (27). This evidence concerns the gene DOCK8 and allergic disease.