EXPRESS: Value of T-lymphocyte subsets, immunoglobulin, and complements in assessing efficacy and prognosis of connective tissue disease-associated interstitial lung disease

OBJECTIVE: This study evaluated the clinical value of combined T‑lymphocyte subset, immunoglobulin, and complement testing in assessing treatment efficacy and prognosis in connective tissue disease‑associated interstitial lung disease (CTD‑ILD). METHODS: A total of 110 CTD‑ILD patients, 90 CTD patients without ILD, and 110 healthy controls were enrolled. High‑resolution chest CT and lung function tests were performed in CTD‑ILD and CTD patients. Serum CD4+, CD8+, IgA, IgG, IgM, C3, and C4 levels were measured. CTD‑ILD patients received prednisone plus cyclophosphamide and were categorized into good/poor efficacy groups and good/poor prognosis groups after 6‑month follow‑up. Independent risk factors for poor prognosis were identified by logistic regression, and ROC analysis assessed the predictive value of combined indicators. RESULTS: Compared with CTD and control groups, CTD‑ILD patients had reduced lung function, lower T‑lymphocyte subsets, elevated immunoglobulin, and reduced complements (P < 0.05). Poor efficacy and poor prognosis groups showed lower CD4+/CD8+ levels, higher immunoglobulins, and lower complements than their counterparts (P < 0.05). CD8+, IgA, C3, and C4 were independent predictors of treatment efficacy, while CD4+, CD8+, IgA, C3, and C4 independently predicted prognosis. ROC analysis confirmed the combined assay's predictive value. CONCLUSION: Combined measurement of T‑lymphocyte subsets, immunoglobulins, and complements provides significant predictive information for treatment response and prognosis in CTD‑ILD patients.