CELLULAR AND BIOCHEMICAL CHARACTERISTICS OF BRONCHOALVEOLAR LAVAGE FLUID IN SYMPTOMATIC NONALLERGIC ASTHMA

We have undertaken cellular and biochemical examination of bronchoalveolar lavage fluid from nonallergic patients with asthma to determine the nature and degree of inflammatory process in symptomatic asthma. Six patients with asthma (mean methacholine provocative concentration causing a 20% fall in FEV1 was 0.26 mg/ml) and six control subjects underwent fiberoptic bronchoscopy with bronchoalveolar wash. The patients with asthma shed a higher number of epithelial cells into lavage fluid than normal control subjects (p < 0.05). Their lavage fluid also contained increased numbers of neutrophils (p < 0.025), eosinophils (p < 0.025), and basophilic cells (p < 0.025), and increased proportion of activated T cells (p < 0.05). The basophilic cells were mast cells, as indicated by positive labeling with the monoclonal antibody MCG35. Biochemical analysis of lavage fluid demonstrated exudation of protein molecules in airways of patients with asthma with increased contents of albumin (p < 0.05) and fibronectin (p < 0.05). In the lavage fluid of patients with asthma, there were also increased amounts of interleukin-1-beta (IL-1-beta) (p < 0.025), interleukin-6 (IL-6) (p < 0.025), and granulocyte-macrophage, colony-stimulating factor (GM-CSF) (p < 0.05), as compared with lavage fluid of normal control subjects. Immunocytochemical evaluation of lavage cells demonstrated that IL-1-beta, IL-6, and GM-CSF were mostly produced by nonciliated epithelial cells and/or monocytes. IL-1, IL-6, and GM-CSF can prime granulocytes to respond to other stimuli and can promote T cell activation. The production of these cytokines by bronchial resident cells may have a role in the perpetuation of the inflammatory responses in asthma.