CD4 and interstitial lung disease: Low levels of serum KL-6 and SP-D, high levels of serum AST, γ-GTP, and CD4+/CD8+ ratio in BAL fluid, and the predominance of subpleural GGO or irregular linear opacity in HRCT may provide clues for discriminating anti-MDA-5 antibody-positive CADM-ILD with poor prognosis.