Effect of erythromycin on bronchial hyperresponsiveness in patients with bronchial asthma

The effects of erythromycin (erythromycin stearate, Erythromycin; CAS 643-22-1) on the bronchial hyperresponsiveness and the functions of lymphocytes and neutrophils were evaluated. Administration of erythromycin to asthmatic patients in a dosage of 600 mg/d for 10 weeks reduced the bronchial hyperresponsiveness measured by histamine inhalation test. Furthermore, incubation with erythromycin for 96 h inhibited the mixed lymphocyte reaction at the concentration of more than 10 mumol/l in a dose-dependent manner, and the value of IC50 was about 30 mumol/l. 2-h incubation with erythromycin showed a weak inhibition to n-formyl-methionyl-leucyl-phenylalanine (FMLP)-induced superoxide production of polymorphonuclear neutrophils (PMNs) at the concentration of more than 30 mumol/l in a dose-dependent manner. 1-h incubation with 1 mumol/l and 100 mumol/l of erythromycin inhibited FMLP-induced chemotaxis of PMNs. The rates of inhibition at the concentration of 1 mumol/l and 100 mumol/l were 29.7% and 41.7%, respectively. Erythromycin thus showed a beneficial effect on bronchial hyperresponsiveness. This effect might be due to the regulation of the inflammatory cells.