Study On Clinical Diagnosis Value Of Active Tuberculosis By PBMCs Tuberculosis Antibody Secretion Test And Enzyme-linked Immunespot Assay

Objective: To study on the clinical diagnosis value of active tuberculosis (TB)by peripheral blood mononuclear cells (PBMCs) secreting tuberculosis antibody testand Enzyme-linked immunespot (ELISPOT) assay.Methods:163participants were enrolled in this study, including104patientswith active TB (27cases of smear positive TB,61cases of smear negative TB,16cases of extrapulmonary TB),26patients with Mycobacterium tuberculosis (MTB)latent infected (LTBI) and33healthy controls (HC). PBMCs were isolated by Ficolldensity gradient centrifugation method, and cultured in vitro for4days, thencollecting the cell culture supernatants of each group. Antigen-specific tuberculosisantibodies in supernatant were detected by indirect ELISA and Western blot. Bystimulation with early secretory antigenic target-6(ESAT-6) and ESAT-6/CFP-10fusion antigen, T cells with IFN-γ were detected by ELISPOT. The sensitivity,specificity, positive predictive value and negative predictive value of the threemethods were measured by statistics.Results:1.The OD value of Mycobacterium tuberculosis-specific antibodies in active TBgroup was higher than both LTBI and HC group by ELISA (p<0.001); Areas under thecurve (AUC) of TB-specific antibodies distinguish active TB, LTBI and HC were0.857and0.944, when the cut-off value was confirmed as0.42, distinguishingbetween active TB and LTBI with a sensitivity of77.9%and a specificity of80.8%,and the positive predictive value was94.2%, the negative predictive value was47.7%;distinguishing between active TB and HC with a sensitivity of77.9%and a specificityof93.9%, and the positive predictive value was97.6%, the negative predictive value was57.4%.2. The Western Blot assay had the79.2%for sensitivity,100.0%for specificity,100.0%for positive predictive value and40.7%for negative predictive value in thediagnosis of active TB（p<0.001）.3. The ELISPOT assay had the82.7%for sensitivity,87.9%for specificity,95.6%for positive predictive value and61.7%for negative predictive value in the diagnosisof active TB（p<0.001）.4. The sensitivity, specificity and positive predictive value of the three methodsfor diagnosis of active TB were compared in parallel, the difference was notstatistically significant (p>0.05); their negative predictive values were compared inparallel, the Western blot assay was lower than ELISA and ELISPOT methods(p<0.05). Comparing the positive rate of MTB positive group and MTB negativegroup with ELISA and ELISPOT methods, the difference was not statisticallysignificant (p>0.05).5. The positive rate of active TB with ELISA, Western Blot and ELISOPTmethods in16cases of extrapulmonary TB were respectively81.3%,56.3%,68.8%.Conclusions:1. PBMC tuberculosis antibody secretion test by ELISA showed high diagnosticperformance in the diagnosis of active TB, which can distinguish active TB, LTBI andhealthy people.2. PBMC tuberculosis antibody secretion test by Western blot was simple inoperation, which was highly specific in diagnosing active TB.3. PBMC tuberculosis antibody secretion test and ELISPOT assay showed highdiagnosis value of active TB, PBMC tuberculosis antibody secretion test was suitableas a new method for diagnosis of active TB.