IL17A and pulmonary tuberculosis: A recent study by Singh et al discovered the role of this cytokine in regulation of MMP secretion by using biopsies from patients having pulmonary TB, patient's bronchoalveolar lavage fluid (BALF) and primary human airway epithelial cells.96 IL‐17 was expressed in TB patient granulomas, and MMP‐3 was expressed in adjacent pulmonary epithelial cell, while IL‐17 exhibited a concentration‐dependent effect on MMP‐3 secretion.