Comparison of an in-house tuberculosis-specific IFN-γ release assays with T-SPOT TB in latent tuberculosis infection diagnosis among HIV-infected individuals / 中华检验医学杂志

ABSTRACT

Objective To evaluate the diagnostic value of two tuberculosis-specific IFN-γ release assays in latent tuberculosis infection among HIV-infected individuals. Methods The levels of tuberculosis antigen-specific IFN-γin 102 HIV patients from AIDS Outpatient Clinic of Shenzhen Third People's Hospital were detected by in-house tuberculosis-specific IFN-γ ELISpot assay and commercial T-SPOT TB kit, and tuberculin skin test (TST) were done at the same time. There were 66 males and 36 females,and the average age was 35. Results Seventeen HIV infected patients were positive in both IFN-γ ELISpot and T-SPOT TB methods, the sensitivity, specificity positive predictive value(PPV), negative predictive value(NPV) and compliance rates of ELISpot were 94. 4% ,94. 0% ,77. 3% ,98. 8% and 94. 1% ,respectively. Three patients were positive in both IFN-γELISpot and T-SPOT TB methods, the sensitivity, specificity, PPV, NPV and compliance rates of TST were 16. 7%, 98. 8%, 75.0%, 84. 7% and 84. 3%, respectively. The average number of spots using three kinds of antigen ESAT-6, Pool A,Pool B obtained were 26. 89 ±5. 77,18. 96 ±4. 75 and 14. 51 ± 3.77, respectively. Only ESAT-6 and Pool B have a statistically significant difference (H=7.557,P = 0.022 9), no significant difference was shown between other groups. There was no significant difference between the positive rate and the CD4+ T cellls number(x2 =0. 860 8 ,P =0. 650 2) ,as the same as the T-SPOT TB (x2 = 1. 396 4, P = 0. 497 5 ). Conclusions The performance of this in-house tuberculosis-specific IFN-γ ELISPot assay was comparable to T-SPOT assay in diagnosis of latent tuberculosis infection, and the sensitivity and specificity of both these two assays were all much higher than TST. They canbe recommended in diagnosing latent tuberculosis infection in HIV infected patients.