FOXP3 and allergic disease: A detailed knowledge of human FOXP3+ cell subsets is essential for a better understanding of the regulation of human FOXP3 expression, the study of abnormalities among the FOXP3+ subpopulations in autoimmune diseases and allergies, and the selection and purification of the most promising subpopulation(s) of Treg cells for in vitro expansion and adoptive transfer (Fujii et al., 2011; Miyara and Sakaguchi, 2011).