Specific IgA and concentrations of the MMP-9, both total and active, and its inhibitor TIMP-1 were measured in sputum supernatant recovered from stable COPD patients colonized and non-colonized by H. influenzae. The PAC-COPD Study comprises patients who had a first admission for COPD exacerbation and who were examined later after the stabilization of the disease. Here, MMP9 is linked to chronic obstructive pulmonary disease.