[Effects of erythromycin on H2O2 generation by neutrophils]

Low-dose long-term erythromycin therapy has been reported to be effective in diffuse panbronchiolitis, but the mode of action remains obscure. We therefore evaluated the effect of erythromycin the generation of H2O2 by neutrophils. In vitro, erythromycin (0.1, 1.0, and 20 micrograms/ml) suppressed both spontaneous and PMA-stimulated H2O2 generation. H2O2 generation by neutrophils obtained from peripheral blood and from bronchoalveolar lavage fluid from patients with diffuse panbronchiolitis was higher than that from healthy controls. After erythromycin therapy, H2O2 generation by neutrophils was lower. Compared with the control, H2O2 generation by peripheral neutrophils was low in the patients who responded clinically to erythromycin therapy, but was high in those who did not respond. These results suggest that at least some of the therapeutic effect of erythromycin in patients with diffuse panbronchiolitis is due to reduction in H2O2 generation by neutrophils.