The RA-ILD group had a higher positive rate and increased level of anti-CCP (93.1% vs 75.0%, P = 0.008 and 696.9 ± 531.4 vs 429.3 ± 555.8, P = 0.004, respectively), but there were no significant differences for RF, anti-nuclear, anti-ds-DNA, anti-Sjögren's-syndrome-related antigen A, and anti-Ro52 antibody levels between the two disease subgroups. Here, TRIM21 is linked to interstitial lung disease.