NEUTROPHIL INFILTRATION AND RELEASE OF IL-8 IN AIRWAY MUCOSA FROM SUBJECTS WITH GRAIN DUST-INDUCED OCCUPATIONAL ASTHMA

Background The immune-pathological mechanism for occupational asthma i nduced by grain dust (GD) remains to be clarified. There have been few reports suggesting the involvement of neutrophils inducing bronchocon striction after inhalation of GD. Objective To further understand the role of neutrophil in the pathogenesis of GD-induced asthma. Materials and methods We studied the phenotype of leucocytes of the bronchial m ucosa in patients with GD-induced asthma. Bronchial biopsy specimens w ere obtained by fibreoptic bronchoscopy from six subjects with GD-indu ced asthma. Six allergic asthma patients sensitive to house dust mite were enrolled as controls. Bronchial biopsy specimens were examined by immunohistochemistry with a panel of monoclonal antibodies to tryptas e-containing mast cell (AA1), activated eosinophil (EG2), pan T-lympho cyte (CD3) and neutrophil elastase (NE). Induced sputum was collected before and after the GD-bronchoprovocation test. The IL-8 level in the sputum was measured using ELISA. Results There was a significant incr ease in the number of AAl(+) and NE+ cells in bronchial mucosa of GD-i nduced asthma, compared with those of allergic asthma (P=0.01, P=0.01, respectively). No significant differences were observed in the number of EG2(+) and CD3(+) cells (P = 0.13, P = 0.15, respectively). IL-8 w as abundant in the sputum of all GD-induced asthma patients and signif icantly increased after the bronchial challenges compared with the bas eline value (P = 0.03). Conclusion These findings support the view tha t neutrophil recruitment together with mast cells may contribute to th e bronchoconstriction induced by GD. A possible involvement of IL-8 wa s suggested.