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P127. The application of T-SPOT.TB in the differential diagnosis of Crohn's disease and intestinal tuberculosis

Y. He1, Y. Chen2, Q. Zhang1, Q. Cao3, Z. Ye3, B. Chen1, R. Mao1, Z. Zeng1, L. Xue3, P. Hu1, M. Chen1, 1The First Affiliated Hospital of SunYat-Sen University, Gastroenterology, Guangzhou, China, 2The First Affiliated Hospital of SunYat-Sen University, Medical Ultrasonics, Guangzhou, China, 3The First Affiliated Hospital of SunYat-Sen University, Pathology, Guangzhou, China

Background

To investigate the diagnostic value of T-SPOT.TB kit for intestinal tuberculosis (ITB) and try to analyze the relationship between T-SPOT results and pathologic features.

Methods

The peripheral blood from 40 ITB and 108 Crohn's disease (CD) was collected, mononuclear cells (PBMC) were isolated, then detected by T-SPOT.TB kit. Mycobacterium tuberculosis (MTB) polymerase chain reaction (PCR) of IS6110, tuberculin skin test (TST), and acid-fast staining of biopsied colonic tissue specimens were performed. Pathologic features of all colon biopsy samples were identified by two pathologists blindly. The relationship between T-SPOT results and pathologic features was also analyzed.

Results

Thirty-eight cases (95%) were positive by T-SPOT.TB detection in ITB group, whereas 19cases (20.4%) were positive in CD group (P < 0.05). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of T-SPOT.TB for diagnosing ITB was 95.0%, 85.4%, 67.8% and 98.1% respectively. The positive rate of T-SPOT.TB test (95%) was significantly higer than TST (50%, P < 0.05), Mycobactirium tuberculosis DNA PCR (20%, P < 0.05) and acid fast stain (1%, P < 0.05) in ITB group. TSPOT false positive in CD group was more commonly seen in the specimens with granulomas or multinucleated giant cells in our study (31.6%% vs 14.3%, P < 0.05).

Conclusion

T-SPOT.TB is a practical diagnostic tool with high specificity and negative predictive value. The T-SPOT.TB kit could be used for the differential diagnosis of ITB and CD.