IL4 and asthma: Recently, the newly described T-cell subtype Natural Killer T (NKT) cells has gained substantial interest regarding their role in asthma pathology [23], [24], [25], [26], [27] NKT cells are found in increased amounts in BAL fluid from patients with severe and poorly controlled asthma [28] and are thought to produce high amounts of IL-4 and IL13 in response to allergens, and of IL-13 and IL-17a in response to viral infections and ozone, respectively.