Alveolar macrophages (AM) were cultured in the presence or absence of 10 µM BB-3103 and 1 mM Pefabloc for 30 min before addition of glutathione S-transferase (GST)-proTNF) substrate for a further 2 h. Data are expressed as a percentage of medium alone. Grey bars, medium alone; diagonal bars, 10 µM BB-3103; horizontal bars, Pefabloc; hatched bars, Pefabloc + BB-3103. **P < 0·01 sarcoidosis BB-3103 versus sarcoidosis medium alone; §P < 0·01 usual interstitial pneumonia (UIP) Pefabloc versus UIP medium alone, #P < 0·01 UIP Pefabloc + BB-3103 versus UIP BB-3103 alone, Student's paired t-test (a). In vitro cleavage of GST-proTNF by AM from a subject with UIP. Lane 1, no inhibitors; lane 2, Pefabloc; lane 3, BB-3103; lane 4, BB-3103 + Pefabloc; lane 5, assay in the absence of AM (b). Soluble TNF release by AM from healthy subjects (c), subjects with sarcoidosis (d) and UIP subjects (e) treated with BB-3103 (BB) or Pefabloc (PF), *P < 0·05, **P = 0·01, ***P < 0·001 versus medium alone.