IL-5, IL-8 AND GM-CSF IMMUNOSTAINING OF SPUTUM CELLS IN BRONCHIAL-ASTHMA AND CHRONIC-BRONCHITIS

Background Granulocyte-macrophage colony stimulating factor (GM-CSF) a nd interleukin (IL)-5 or IL-8 have been suggested to play an important role in the pathogenesis of eosinophilic airway inflammation in bronc hial asthma or neutrophilic airway inflammation in chronic bronchitis, respectively, However, GM-CSF and IL-8 have biological activities to either eosinophils or neutrophils. Objective To investigate the contri bution of these cytokines to airway inflammation, we compared the cell ular differential and immunolocalization of GM-CSF, IL-5 and IL-8 in s putum cells from patients with bronchial asthma and chronic bronchitis . Methods Cytospins of sputum cells from 12 patients with bronchial as thma and 12 with chronic bronchitis were subjected to cellular differe ntial counting and immuno-cytochemistry with anti-human GM-CSF, IL-5 a nd IL-8 antibody. Results The predominant cells in bronchial asthma we re eosinophils and lymphocytes, while those in chronic bronchitis were neutrophils. All cytokines examined were detected in either bronchial asthma or chronic bronchitis, although the percentage of GM-CSF and I L-5 positive cells in bronchial asthma (53.4 +/- 6.0 [mean +/- SEM]% a nd 9.7 +/- 2.8%, respectively) was significantly higher than that in c hronic bronchitis (11.4 +/- 2.5%; P < 0.001 and 1.7 +/- 0.3%; P < 0.00 7, respectively). In contrast, the percentage of IL-8 positive cells i n chronic bronchitis (23.8 +/- 7.0%) was significantly higher than tha t in bronchial asthma (7.7 +/- 1.9%; P < 0.04). The cells positive for IL-5 were lymphocytes in bronchial asthma and chronic bronchitis. The cells positive for GM-CSF in bronchial asthma and were predominantly eosinophils, while those in chronic bronchitis were monocytes/macropha ges and neutrophils. In contrast, neutrophils are mainly positive for IL-8 in chronic bronchitis, while monocytes/macrophages and bronchial epithelial cells are positive for IL-8 in bronchial asthma. Conclusion The immunochemical comparison of GM-CSF and IL-8 localization in sput um cells between bronchial asthma/chronic bronchitis suggests the diff erential regulation and roles of these cytokines in eosinophilic vs ne utrophilic airway inflammation, resulting in the development of differ ent types of airway inflammation.