MMP9 and chronic obstructive pulmonary disease: With the hypothesis that in stable COPD bronchial colonization by H. influenzae may be related to an impaired local specific immunoglobulin response and to an imbalance between MMP-9 and TIM-1 levels in bronchial secretions, we carried out a cross-sectional analysis of specific IgA against H. influenzae and metalloproteinase activity in sputum samples recovered from patients included in the PAC-COPD Study.