Fig. 1.

Evaluation of the RF or ACPA levels in patients with RA. Distribution of RF (A), RF IgA (B), ACPA IgG (C), ACPA IgA (D), ACPA SC (E), and anti-CarP Ab (F) levels. The filled circle, filled triangle, filled square, filled diamond, and empty circle represent RA with UIP, RA with NSIP, RA with airway disease, RA with emphysema, and RA without CLD, respectively. ACPA: anti-cyclic citrullinated peptide antibody, CLD: chronic lung disease, CLD(−): without CLD Ig immunoglobulin, NSIP: nonspecific interstitial pneumonia, RA: rheumatoid arthritis, RF: rheumatoid factor, SC: secretory component, UIP: usual interstitial pneumonia, CarP: carbamylated protein, Ab: antibody