Introduction: IL-18 is a proinflammatory cytokine involved in pathogenesis of chronic diseases. Its overproduction may induce pulmonary diseases such us pulmonary fibrosis  and COPD.

Material and methods: The study included 15 patients in stable COPD and 10 patients with stabile asthma. The average age was 67 years, average pack years of smoking 42,5. The patients were in moderate stadium of the disease. Patients after infection or using glucocorticoids were excluded. We measured cellular proportion in induced sputum and conducted pulmonary function tests. Concentration of IL-18 was measured using ELISA method.

Results: Median percentage of inflammatory cells in sputum of COPD patients amounted to: macrophages – 32, lymphocytes – 1,5, neutrophiles -50 and eosinophils – 18,5%. An average concentration of IL-18 in sputum of patients with COPD was 22,4 pg/mL and did not differ when compared with asthma patients – 21,7. We observed a tendency to negative correlation of IL-18 concentration with percentage of lymphocytes and a correlation of IL-18 concentration with percentage of eosinophils.

Conclusions: The observation  confirmed  the suggested influence of IL-18 on airways inflammation in COPD.