RESUMEN
Objective To evaluate the clinical significance of the level of [gG4 in the bronchoalveolar lavage fluid (BALF) of patients with rheumatic disease related interstitial lung disease (RD-ILD).Methods Eighteen patients with RD-ILD,14 patients with pulmonary infection and 12 patients without ILD or pulmonary infection,were recruited consecutively from the in-patient ward of Peking University People's Hospital.Clinical features and laboratory data were extracted from the medical record database of Peking University People's Hospital.The level of IgG4 was determined by ELISA.The statistical analysis of data using t test,and the correlation between the two variables were analyzed using linear regression analysis.Results The level of IgG4 was significantly higher in BALF of patients with RD-ILD than patients' without ILD or pulmonary infection,whereas there was no difference compared to patients with pulmonary infection.The level of IgG4 in BALF of patients with RD-ILD was positively correlated with the percentage of lymphocytes (r=0.53,P=0.03),and significantly negatively correlated with the percentage of macrophages (r=-0.65,P=0.005).Conclusion The level of IgG4 is significantly elevated in BALF of patients with RD-ILD,which is probably secreted from the lymphocyte of the lung.