Evidence of increased histamine levels of lung lavage fluids from patients with cryptogenic fibrosing alveolitis.

In this study we report a significant increase in histamine in lung lavage fluids from a group of 33 patients with lone cryptogenic fibrosing alveolitis (lone CFA), and from a group of 13 patients having CFA in association with other connective tissue disorders, when compared with findings for 13 smoking patient controls without peripheral lung disease (P less than 0.001, P less than 0.05 respectively). The increases were independent of smoking or treatment. Significant correlations were obtained between the raised histamine levels in CFA and increased levels of albumin and increased counts of neutrophils and eosinophils in the lavage fluids, and with more pronounced fibrosis in CFA lung biopsies.. Thus histamine is associated with features of inflammation relating to progressive or more severe disease. No significant increase in histamine was observed in a group of 22 patients with sarcoidosis, although 21 had evidence of disease involving the lung parenchyma. There were, however, significantly higher levels in the patients with X-ray evidence of upper lobe contraction, suggestive of "fibrosis" (P less than 0.025). The levels also showed a correlation with increasing counts of lavage neutrophils (P less than 0.005), a feature also associated with X-ray evidence of contraction in this group. Mast cells were readily identified in biopsies from 12 CFA patients suggesting that these cells may provide one possible source of histamine in CFA lungs. These observations raise the question whether histamine, and/or possibly other substances derived from mast cells, plays any role in amplifying inflammation associated with pulmonary fibrosis.