IL15 and idiopathic pulmonary fibrosis: Although IL-6, -8, -15, VEGF and TNF-α were shown to contribute to the pathogenesis of IPF [7,31,34,35,36] their EBC levels in our study were either below the detection limit (IL-15 and TNFα) or did not differ significantly between patients with IPF and controls (IL-6, VEGF-A).