Objective: To evaluate the role of cytokines in the pathogenesis of COPD.
Methods: Induced sputum samples were obtained from 20 patients with stable COPD, 10 healthy smokers (HS) and 10 healthy nonsmokers (HNS). Total and differential cell counts were examined, and sputum interleukin (IL)-8, tumor necrosis factor (TNF)-alpha, IL-6 level were measured by radioimmunoassay technique.
Results: Sputum IL-8, TNF-alpha level and neutrophil percentages (PMN) in the COPD group were significantly higher than those in the HS group and the HNS group (P < 0.01). Compared with the HNS group, there was a significant increase in the PMN and the level of IL-8 in the HS group (P < 0.05). The sputum level of IL-6 did not differ significantly among three groups (P > 0.05). In the COPD group, the sputum level of IL-8 was correlated positively with the level of TNF-alpha and the PMN (r's = 0.5999, 0.6737). In the HS group the sputum level of IL-8 was also correlated positively with the PMN (rs = 0.8424). The sputum IL-8, TNF-alpha levels and the PMN were all correlated negatively with FEV1% and FEV1/FVC in the COPD group (r's = -0.6453, -0.7341, -0.7341, -0.7624, -0.5262, -0.7353).
Conclusions: IL-8, TNF-alpha and neutrophil are involved in airway inflammation which results in airflow obstruction, thus playing an important role in the pathogenetic process of COPD.