Clinical application of T cell enzyme-linked immunospot assay in extrapulmonary on rapidly diagnosis of patients with tuberculosis

Abstract

Objective To investigate the diagnostic value of T cell enzyme-linked immunospot (T-SPOT.TB) assay on extrapulmonary tuberculosis patients.Methods Thirty patients suffered from extrapulmonary mycobacterium tuberculosis(MTB) infection and 30 with non-MTB infection were recruited this study.T-SPOT.TB assay was used to detect early secreting antigen target-6 (ESAT-6) and culture filtrate protein-10(CFP-10) specific T cells in blood samples.PPD skin test was also used.Results (1)The positive rate of MTB detected by T-SPOT.TB assay was 91.89％ (34/37),higher than that of un-tuberculosis group (6.67 ％ (2/30)),and the difference was significant (x2 =48.403,P ＜ 0.001).(2) The sensitivity,specificity,positive prospective value and negative prospective value of T-SPOT.TB assay were 91.89％,93.33％,94.44％ and 90.32％ respectively,better than those of PPD skin test (67.57％,56.67％,65.79％,58.62％),and the differences were markedly (x2 =6.773,10.756,9.392,8.031 respectively ; P =0.009,0.001,0.002,0.005 respectively).Meanwhile T-SPOT.TB assay has low agreement with means of PPD skin test(Kappa =0.311,x2 =6.801,P =0.009).Conclusion T-SPOT.TB assay has a higher sensitivity and specificity in the rapid diagnosis of extrapulmonary tuberculosis.Therefore,it is with great value and applicability as a screening test. Key words: T lymphocytes ; Enzyme-linked immunospot assay; Extrapulmonary; Mycobacterium tuberculosis; Infection