enzymes. roles in asthma asthmatic subjects in 9 to 11 years old, 80% to 85% of asthma exacerbations that were associated with reduced peak expiratory flow rates and wheezing were due to viral upper respiratory tract infections (uris). high rates of asthma attacks due to rhinovirus infection are also found in adults. it turns out that rhinovirus are capable of inducing epithelial cells to produce proinflammatory cytokines that result in airway hyperresponsiveness, neurogenic inflammatory responses, mucous secretion, inflammatory cell recruitment and activation, and plasma leakage. to support this statement, asthmatic subjects that are infected with rhinovirus have demonstrated an increase in airway hyperresponsiveness, airway obstruction, and inflammation. similarly, rhinovirus infection has caused subjects with allergic rhinitis but no history of asthma to have a significantly increased airway hyperreactivity as well as a significantly increased incidence of late asthmatic reactions. this shows that in addition to causing airway hyperreactivity, rhinovirus also promotes the onset of non-atopic asthma. furthermore, rhinovirus infection also promotes eosinophil recruitment to airway segments after antigen challenges, and thus intensifies airway inflammatory response to antigens, leading to the development of asthma.