Fig. 4.

Inhibition of alveolar macrophage (AM) mediator production by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). AMs were treated for 20 h with NNK in the presence of lipopolysaccharide (LPS) (10 ng/ml) for the release of tumour necrosis factor (TNF) (a) or in the presence of bacille Calmette–Guérin (BCG) for the release of interleukin-12 (IL-12) b). NNK significantly inhibited (†P < 0·005, ‡P < 0·001 and *P < 0·05) the production of tumour necrosis factor (TNF) and IL-12 by AMs. Mean values ± standard error of the mean (s.e.m.) of five to eight experiments are shown. (c) AMs were treated with NNK for 48 h in the presence of LPS (10 ng/ml) for the release of nitric oxide (NO). NNK significantly inhibited (*P < 0·05 and ‡P < 0·001) AM NO production in a concentration-dependent manner. Mean values ± standard error of the mean (s.e.m.) of 13 experiments are shown.