IL5 and airway hyperresponsiveness: At the beginning of 2000s, the therapeutic role of IL-5 antagonists in asthma was postulated following the observation in rats of the eosinophils reduction in BAL and lung tissue and reduction of airway hyperresponsiveness after treatment with anti-IL5 monoclonal Antibodies (mAbs) intranasally, intravenously, or intraperitoneally, suggesting a good outcome also in treatment of human asthma [14].