1. Mast cell activation in the lung was investigated by measuring concentrations of mast cell tryptase and histamine in the bronchoalveolar lavage fluid from patients with bronchial carcinoma, sarcoidosis, extrinsic allergic alveolitis or cryptogenic fibrosing alveolitis and from normal subjects. 2. Histamine concentrations in bronchoalveolar lavage fluid supernatants were elevated in the bronchial carcinoma and cryptogenic fibrosing alveolitis groups, and were correlated with the histamine content of the cells recovered. 3. An avidin-biotin-enhanced antigen-capture e.l.i.s.a., using polyclonal rabbit antibody specific for tryptase, and mouse monoclonal antibody AA5, allowed the quantification of tryptase in all samples of bronchoalveolar lavage fluid. Tryptase concentrations were increased in the bronchial carcinoma and extrinsic allergic alveolitis groups and in some of the patients with sarcoidosis, and the levels correlated with mast cell numbers and also with concentrations of albumin. 4. There was no significant correlation between levels of tryptase and histamine, suggesting differences in the rates of metabolism or different cellular sources. 5. The tryptase and histamine concentrations measured suggest that there is continuous degranulation of mast cells within the normal lung, but that this process is more pronounced in patients with bronchial carcinoma or interstitial lung disease.
1. Histamine, both free and cell associated, has been demonstrated in middle ear fluid from patients with secretory otitis media (SOM). 2. Histamine, mainly free in solution, has also been shown to be present in nasopharyngeal secretions taken from close to the Eustachian tube openings into the nasopharynx. 3. The adenoids from patients with middle ear effusion contained significantly ( P <0.05) more histamine than those with no effusion. 4. However, in preliminary experiments, we could demonstrate no differences in the histamine secretory response of adenoids from SOM and non-SOM patients to anti-immunoglobulin E (anti-IgE), house dust mite antigen and calcium ionophore A23187 in vitro. 5. These results support the hypothesis of an inflammatory basis for SOM.