Decreased granulocyte response to isoproterenol in asthma during upper respiratory infections

Isoproterenol inhibits zymosan-stimulated release of lysosomal enzymes from granulocytes. Using this as an in vitro cell model to study beta-adrenergic response, granulocyte reaction to isoproterenol was examined in asthma. There was a significantly decreased response to isoproterenol (10(-7) to 10(+-5) M) in patients with mild asthma who had not taken bronchodilators for 2 weeks before study and also in patients with severe asthma requiring bronchodilators and corticosteroids. During respiratory infections that provoked an attack of asthma, the granulocyte response to isoproterenol was further decreased. The change in granulocyte response to isoproterenol may reflect a similar change in beta-adrenergic tone of the airways and provide one explanation for asthma during colds.