Viral respiratory infections in the development of bronchial asthma in children

Viral respiratory infections are the most important triggers of wheezing an d exacerbations of asthma in children. In addition,they may be involved in the development of allergic asthma. Studies in humans and in animal models indicate that a T cell mediated immune response to respiratory viruses and subsequent airway inflammation likely play a critical role in the induction of wheezing and allergic airway sensitization. Modulation of the host's im mune response to allergen and impaired barrier function of the respiratory epithelium favor the development of allergic airway inflammation and thus o f bronchial asthma. Eosinophilic airway inflammation seems to be crucial fo r the development of wheezing. Mediators of inflammation, inflammatory infi ltrates, epithelial dysfunction, increased mucus production, transudation a nd edema all contribute to airway narrowing and airway obstruction. Understanding both immunological and non-immunological mechanisms involved will be essential for the development of new therapeutic approaches for vir us induced reactive airway disease.