Mast cell and histamine content of human bronchoalveolar lavage fluid

Bronchoalveolar lavage was performed in 97 patients including control patients with bronchial carcinoma (24) and patients with sarcoidosis (20), cryptogenic fibrosing alveolitis (9), and asthma (4), and others. Cytocentrifuged slides were stained by two methods: May-Grunwald Giemsa and toluidine blue. In the last 32 subjects the bronchoalveolar lavage fluid was separated into supernatant and cell pellet for the subsequent assay of the preformed mast cell mediator, histamine. Comparison of the two methods of staining showed a bias towards toluidine blue. Controls had a differential mean (SE) mast cell count of 0.07% (0.01%). Higher counts were noted in cryptogenic fibrosing alveolitis-0.61% (0.15%) (p <0.001)-and in sarcoidosis- 0.14% (0.02%) (p <0.05). There was a strong correlation between absolute mast cell counts and cell lysate histamine concentration (r = 0.78, p <0.001). Less strong, but significant, correlations between supernatant histamine concentration and absolute mast cell counts (r = 0.48, p <0.01) or cell lysate histamine concentration (r = 0.72, p <0.01) were also found. Derived mean values of histamine per mast cell ranged from 3.7 to 10.9 picograms. The mean histamine content of lavage fluid supernatant as a percentage of the total lavage fluid histamine was 24.9% (3.3%). The possible clinical significance of these findings is discussed.