Clinical Application of T-SPOT.TB Using Pleural Effusion as a Diagnostic Method for Tuberculosis Infection

Introduction: The objective of this study was the comparison of the results of T-SPOT.TB using pleural effusion (PE) with those of IGRAs using peripheral blood (PB) or other diagnostic methods for the diagnosis of tuberculous (TB) pleurisy. Methods: We measured adenosine deaminase (ADA) in PE, QuantiFERON TB-Gold In-Tube (QFT), and T-SPOT.TB using PB, and T-SPOT.TB using PE. The definite group of TB pleurisy included 12 patients and other disease group 33 patients. Main findings: Sensitivity for QFT using PB was 83% and specificity was 85%, sensitivity for T-SPOT.TB using PB was 92% and specificity was 82%, while sensitivity for ADA in PE was 83% and specificity was 76%. When we adopted the same cut-off level of a positive response for T-SPOT.TB as PB using PE, sensitivity for T-SPOT.TB using PE was 100% and specificity was 82%, respectively. Although there were no significant differences among the four diagnostic methods, sensitivity for T-SPOT.TB using PE gave the most accurate diagnosis of TB-definite patients compared to ADA in PE or QFT using PB. Conclusions: If we performed T-SPOT.TB using a local specimen from the infection site, we could obtain a higher sensitivity than IGRAs using PB or ADA in PE and the numbers of ESAT-6 and CFP-10-positive SFCs were 3 to 5 fold higher in PEMCs than in PBMCs. T-SPOT.TB using PE may become a useful diagnostic method for TB pleurisy.