Both sputum MPO and NGAL concentrations correlated strongly with MMP-8 (r = 0.83, P<0.0001 and r = 0.68, P<0.0001 respectively) (Fig 4C and 4D), indicating that MMP-8 in induced sputum of TB patients is likely to be principally derived from neutrophils. This evidence concerns the gene LCN2 and tuberculosis.