CD79A and idiopathic pulmonary fibrosis: RF IgA was associated with ILD (206.6 ± 400.5 vs. 95.0 ± 523.1 U/ml, respectively, P = 1.13 × 10− 8), particularly UIP (263.5 ± 502.0 U/ml, P = 1.00 × 10− 7).