Interstitial lung disease (ILD) is frequently associated with
collagen disease. It is then designated as
collagen vascular disease-associated ILD (CVD-ILD), and influences patients' prognosis. The prognosis of acute-onset diffuse ILD (AoDILD) occurring in patients with
collagen disease is quite poor. Here, we report our investigation of auto-antibody (Ab) profiles to determine whether they may be useful in diagnosing CVD-ILD or AoDILD in
collagen disease. Auto-Ab profiles were analyzed using the Lambda Array Beads Multi-Analyte System, granulocyte immunofluorescence test, Proto-Array Human
Protein Microarray, AlphaScreen assay, and
glutathione S-transferase capture
enzyme-linked
immunosorbent assay in 34 patients with
rheumatoid arthritis (RA) with or without CVD-ILD and in 15 patients with
collagen disease with AoDILD. The average anti-major histocompatibility complex class I-related chain A (
MICA) Ab levels were higher in RA patients with CVD-ILD than in those without (P = 0.0013). The ratio of the average anti-
MICA Ab level to the average anti-
human leukocyte antigen class I Ab level (ie,
MICA/Class I) was significantly higher in RA patients with CVD-ILD compared with those without (P = 4.47 × 10(-5)). To the best of our knowledge, this is the first report of auto-Ab profiles in CVD-ILD. The
MICA/Class I ratio could be a better marker for diagnosing CVD-ILD than KL-6 (Krebs von den lungen-6).