Diagnostic performance in active TB of QFT-Plus assay and co-expression of CD25/CD134 in response to new antigens of Mycobacterium tuberculosis

AbstractThe new QuantiFERON-TB Gold Plus employs modified peptides optimized to elicit an IFN γ response from CD8+ cytotoxic T lymphocytes in addition to CD4+ T cells. With a view to improve the difficult identification of TB cases, we assessed the combination of two specific immunological markers comprising IFN γ secretion and T cells co-expression of CD25 and CD134 in response toMycobacterium tuberculosis-specific antigens. A total of 34 subjects with suspected TB and 10 age-matched HD were prospectively enrolled. Assessing the performance of QFT-Plus in terms of the TB1 and TB2 results, we found that in TB patients, the quantitative IFN γ value in TB2 was similar to that in TB1, and we did not find any differences irrespective of the disease (pulmonary or extra-pulmonary). The flow cytometric CD25/CD134 assay, allowed a more accurate differentiation betweenM. tuberculosis-infected and uninfected patients, with a better combination of sensitivity and specificity, especially by evaluation of CD4+ T-cell subset. All individuals with negative QFT-Plus results displayed a positive CD25/CD134 response. Overall, a positive correlation was found between T cells co-expressing CD25/CD134 and IFN γ levels in response to both QFT-Plus TB antigen tubes, as well as between the QFT-Plus TB1 and TB2 tubes. We demonstrated that both TB1 and TB2 induce a higher expression of CD25+CD134+ markers on CD4+ T cells among infected TB subjects, compared to the lower degree of CD8+ T cells, mai...
Source: Medical Microbiology and Immunology - Category: Microbiology Source Type: research