RESUMEN
OBJECTIVE: To investigate the diagnostic value of interferon-gamma (IFN-gamma), interleukin-12 (IL-12) and adenosine deaminase isoenzymes (ADA(2)) in tuberculous pleural effusions. METHODS: One hundred and ninety specimens of pleural effusion were collected from 190 patients with pleural effusion in Peking University People's Hospital, Beijing Chest Hospital, and Beijing Tuberculosis and Thoracic Tumor Institute, from March 2002 to February 2003. Of them 141 pleural specimens were diagnosed as tuberculous, and 49 as malignant. IFN-gamma and IL-12 concentrations and ADA isoenzyme activity in all the specimens were determined by ELISA and enzyme kinetic analytical method respectively. RESULTS: (1) ADA(2) activity (47.9 +/- 6.9) U/L in tuberculous effusions was significantly higher than that in malignant effusion (13.2 +/- 3.2) U/L (P < 0.01). The IFN-gamma level (112.1 +/- 45.8) ng/L in tuberculous effusion was significantly higher than that in malignant diseases (24.8 +/- 5.9) ng/L (P < 0.01). The IL-12 level (104.3 +/- 32.3) ng/L in tuberculous effusions was significantly higher than that in malignant diseases (61.8 +/- 10.8) ng/L (P < 0.05). (2) By analysis of ROC curves, the cut-off values for IFN-gamma, IL-12 and ADA(2) were defined. The sensitivity and specificity of IFN-gamma for tuberculous effusion were 84.4% and 95.9% respectively. Those of IL-12 for tuberculous effusion were 85.1% and 65.3% respectively, while those of ADA(2) were 84.4% and 91.8%. CONCLUSIONS: IFN-gamma and IL-12 could be used as valuable parameters for the differentiation of tuberculous effusion from malignant, and IFN-gamma was more sensitive and specific for tuberculous effusion than IL-12 and ADA(2).