Erythromycin has been shown to be beneficial for panbronchiolitis, a disorder linked to infection with Pseudomonas aeruginosa. Erythromycin, but not the anti-Pseudomonas antibiotics imipenem, ceftazidime, gentamicin and ciprofloxacin, caused a dose-dependent decrease in the production of tumour necrosis factor (TNF)-alpha by whole blood stimulated with heat-killed P. aeruginosa. The release of interleukin (IL)-10, IL-6, interferon-gamma and IL-8 was inhibited only at the highest erythromycin concentration. Inhibition of TNF-alpha production by erythromycin may, at least in part, explain the efficacy of this macrolide during panbronchiolitis despite its lack of activity for P. aeruginosa.