Recent reports, all using ovalbumin have shown aggravation of asthma by pentraxin 3 [17], prostaglandin E2 [18], IL-15-deficiency [19] or suppression of asthma by anti-inflammatory protein 2 from hookworms [20▪▪], natural killer (NK) receptor 1 [21] and inhibition of hypoxia inducible factor-1α [22]. Here, IL15 is linked to asthma.