Abstract: Objective To determine the differential diagnosis value of Mycobacterium tuberculosis antibody (TB-Ab-IgG),carcinoembryonic antigen (CEA) and adenosine deaminase (ADA) between benign and malignant pleural exudate.Methods The TB-Ab-IgG measured by DIGFA,ADA activity by the modified Giusti assays and CEA measured by IRMA in 92 cases of pleural exudate were analyzed.Results The positive rates of TB-Ab-IgG of tuberculous,malignant exudate and other group were 81.8%, 12.8% and 1.1% respectively,the specificity was 87.5%;the ADA activity of tuberculous and malignat exudate was (59.6±28.8)U/L and (24.7±11.5)U/L( P <0.01).The CEA levels were (8.7±7.3)ng/ml and (60.2±39.6)ng/ml( P <0.01);While the ADA activity of other group was (44.6±26.5)U/L,Compared with tuberculous exudate ( P >0.05).Conclusion The test of TB-Ab-IgG,ADA and CEA of pleural exudate is of great value of differentiate benign from malignant exudate.

Key words: Mycobacterium tuberculosis,Antiboby-Immunoglobulin G, Carcinoembryonic antigen, Adenosine deaminase, Pleural exudate