TLR2 and chronic obstructive pulmonary disease: In COPD GOLD III, strong direct correlations were found between the percentage of peripheral blood CD4+CD282+ cells and serum content of IL-17A (r = 0.96 and p < 0.05), IL-21 (r = 0.94 and p < 0.05), and IL-6 (r = 0.87 and p < 0.05).