Since then, reports on the immunological mechanism of bronchiolitis have also shown that the expression of IL-2 and interferon-γ in serum decreased and the expression of Th2-derived cytokines (IL-4, IL-5, IL-6, IL-8, and IL-10) increased, suggesting that the pathogenesis of bronchiolitis and asthma also exist immune imbalances of Th1/Th26,15. Here, IL5 is linked to asthma.