PRTN3 and idiopathic pulmonary fibrosis: The relationships between corrected BALF ACPA levels and clinical features were investigated.<h4>Results</h4>The proportion of ACPAs (ACPA-IgG level adjusted by total IgG level) in the BALF was significantly lower in patients with IPF than in those with RA-ILD (1222 ± 1424 U/mg vs. 9058 ± 15159 U/mg, p < 0.01).