The role of Foxp3+ Tregs in asthmatic patients is also a matter of controversy; it has been shown that adult patients with severe symptoms present low amounts of Tregs in the airways and blood [13, 14], while other studies show the number of lung regulatory lymphocytes to be increased in severe asthma compared with mild asthmatics and healthy subjects [16], especially following inhaled allergen challenge [17]. This evidence concerns the gene FOXP3 and asthma.