In our study we also observed a higher expression level of IL-6 in induced sputum in COPD patients with the exacerbation history (moderate ambulatory exacerbations requiring treatment with systemic steroids and/or antibiotics or severe exacerbations requiring hospital admission in last 12 months) compared to COPD patients without the exacerbation history. This evidence concerns the gene IL6 and chronic obstructive pulmonary disease.