The present invention relates to methods for treatment or prevention of asthma, mild intermittent asthma, mild persistent asthma, moderate persistent asthma, severe persistent asthma, eosinophilic asthma, neutrophilic asthma, steroid refractory asthma, status asthmaticus, pneumonia, bronchiectasis, COPD, sarcoidosis, and lung cancer based on reducing airway hyper responsiveness, increasing pulmonary compliance, reducing lung inflammation, reducing inflammatory cell count in bronchoalveolar fluid and reducing cytokine production by administration of a mammalian a- and/or ß-defensin.