Performance of whole blood IFN-gamma test for tuberculosis diagnosis basedon PPD or the specific antigens ESAT-6 and CFP-10

OBJECTIVE: To evaluate the QuantiFERON-TB(R) test in BCG-vaccinated, non-BC C-vaccinated and tuberculosis (TB) patient donor groups, and to compare its diagnostic performance with that of a blood test based on the Mycobacteriu m tuberculosis specific antigens ESAT-6 and CFP-10. DESIGN: Analysis of the IFN-gamma responses of whole blood cells from BCG-v accinated or non-BCG-vaccinated donors or patients with tuberculosis, stimu lated with PPD, ESAT-6 or CFP-10 antigens, and evaluation of the specificit y and sensitivity of the test. RESULTS: None of the non-vaccinated donors showed positive responses to M. tuberculosis-PPD, ESAT-6 or CFP-10. In BCC-vaccinated donors, 9/19 (47%) do nors responded to the QuantiFERON-TB(R) test based on M. tuberculosis-PPD, whereas 2/19 (10.5%) responded to either ESAT-6 or CFP-10. Comparable level s of sensitivity were obtained with the QuantiFERON-TB(R) test based on M. tuberculosis-PPD (79%) and ESAT-6 or CFP-10 antigens (72%). CONCLUSION: Our results demonstrate that the whole blood test based on M. t uberculosis-PPD did not efficiently distinguish BCG-vaccinated donors from individuals with disease due to M. tuberculosis. The introduction of new re combinant antigens specific for M. tuberculosis, such as ESAT-6 or CFP-10, should increase the specificity of the whole blood test and enable discrimi nation between TB infection, atypical mycobacterial reactivity and reactivi ty due to BCG vaccination. Such a test would provide a quantum improvement over the current practice of using the tuberculin skin test for TB control and elimination.