CCL13 and chronic obstructive pulmonary disease: Moreover, positive correlation between MCP-4 and eotaxin-3 production was revealed in the bronchial washing fluid samples of COPD patients, and the association was also observed in AECOPD cases (Figure 3; r = 0.679, p < 0.05; r = 0.625, p < 0.05), suggesting the correlation between MCP-4 and eotaxin-3 levels in the airway of COPD patients.