The Application Of T-SPOT.TB In The Diagnosis Of Active TB And Latent TB Infection

Objective: Tuberculosis as one of the major infectious diseases, whichaffect people’s living standards. Traditional mycobacterium tuberculosisdetection for diagnosing tuberculosis has low sensitivity and specificityand it is unable to provide timely and effective data for clinic. In addition,latently infected individuals seem to have become a major source of newcases of tuberculosis. In order to decrease incidence and control TB, earlydiagnosis and prophylactic treatment of latent tuberculosis is critical. Atpresent, tuberculin skin test (TST) is one of tuberculosis infectionscreening methods, but TST has its shortcomings in clinical application:false negative, false positive and complex operation. In recent years, awide used test for detecting active and latent TB infection in developedcountries is TB-infected T cells spot test, which is a novel immunologicaldiagnostic methods developing from the enzyme-linked immunosorbentassay. In our study, by comparing five tests: Acid-fast staining,TB-Ab,TB-PCR, QFT and T-SPOT.TB, we analyzed sensitivity and specificity ofthese five tuberculosis detection. In addition, we compared the diagnosticvalue of T-SPOT. TB with TST in tuberculosis diagnosis. Method: Total of356outpatients and inpatients who had been suspectedof active tuberculosis during the period from March2011to March2013at China-Japan Friendship Hospital of Jilin University was enrolled. Theywere performed by Acid-fast staining, TB-Ab, TB-PCR, QFT andT-SPOT.TB, respectively. According to the track follow-up results, thereare212patients of diagnosed TB and144patients of non-tuberculosis. Atthe same time, we also random collected204healthy controls, including87individuals of a history of exposure to TB and117individuals of nonhistory of exposure to TB. The healthy subjects also performed TST andT-SPOT.TB detection, respectively.Result:1. The sensitivity of Acid-fast staining, TB-Ab, TB-PCR, QFTand T-SPOT.TB tests detecting for diagnosis of active TB were22.6%,67.9%,73.6%,75.4%and86.8%, respectively. T-SPOT.TB is the highestand Acid-fast staining is the lowest, The difference is statisticallysignificant(P<0.05). The specificity of these tests for differential diagnos-es of non-tuberculosis respiratory were100%,72.2%,83.3%,91.7%and88.9%, respectively.The Acid-fast staining is the highest, QFT andT-SPOT.TB are the next. The difference is not statistically significant(P>0.05).2. In the patients, there were individual of HIV and tuberculosisinfection、 blood diseases and tuberculosis-infected. All the patients wereT-SPOT.TB test positive.Three patients were positive in TB-Ab test all of the other tests.3. In healthy subjects, the positive rate of T-SPOT.TB forindividuals with tuberculosis contact history was24.1%and forindividuals without tuberculosis contact history was0.0%; the positiverate of TST for individuals with and without tuberculosis contact historywere79.3%,64.1%, respectively. The positive rates were significantlydifferent between the two tests (P<0.05).Conclusion: TB-infected T cells spot test is a high sensitive and specifictest to diagnose tuberculosis and extrapulmonary tuberculosis. It is notaffected by immunosuppressive condition then it can provide timely andeffective results for the clinical diagnosis of tuberculosis. In addition, italso has a value of diagnosis for latent tuberculosis. Therefore, T-SPOT.TT-SPOT.TB could bring a hope of prevention and control tuberculosis.