CCR2 and chronic obstructive pulmonary disease: Correspondingly, several groups have demonstrated higher MCP-1 concentrations in sputum, plasma, and bronchoalveolar lavage (BAL) of both acute exacerbation and stable stage COPD patients compared to healthy controls [46, 47], and MCP-1 and CCR2 polymorphisms are considered new risk factors for COPD [48].