IL6 and chronic obstructive pulmonary disease: The mean value of pulmonary artery pressure in patients with IL-6 GG genotype was significantly higher than in those with IL-6 CG or CC, when comparing plasma levels of cytokines and the polymorphisms G(−174)C of IL-6, C(−511)T of IL-1beta, and A(−2518)G of MCP-1 in 148 COPD patients with right heart catheterization data and 180 control participants.