Pathogens were commonly grown from bronchoalveolar lavage fluid (BALF) of patients with WG and those with idiopathic pulmonary fibrosis (IPF), BALF levels of interleukin 1 receptor antagonist (IL1ra) were statistically significantly elevated. S aureus was particularly associated with patients with WG both in relapse and in remission. This evidence concerns the gene IL1RN and granulomatosis with polyangiitis.