Oxford Immunotec’s T-SPOT.TB is first test to demonstrate accurate diagnosis of latent TB in HIV patients

Oxford Immunotec Ltd, the Company that monitors T cells for the diagnosis and treatment of disease, today announced the results of a study published recently in the journal AIDS.

The study demonstrates the Company’s T-SPOTTM.TB test for tuberculosis can be used to successfully (97%) detect TB infection in HIV patients, despite the fact they are immunosuppressed.

T-SPOT.TB is currently the only available test for the effective diagnosis of latent TB in HIV patients. Historically the diagnosis of latent TB infection in HIV positive patients has been challenging due to the high levels (between 26% and 41% of all tests) of false negative results given by the traditional Tuberculin Skin Test (‘TST’). This is because the TST requires the interpretation of a bump on the skin caused by an immune response.

The study was performed in 48 subjects, 29 of whom were infected with HIV. Notwithstanding the level of immunosuppression, T-SPOT.TB was able to deliver an evaluable result in 28 of the 29 HIV positive patients (97%) as a result of the test’s high diagnostic sensitivity. Importantly the results achieved with T-SPOT.TB were unaffected by the level of CD4 T cell count and no patient with a CD4 count of less than 200 cells/ìl had an indeterminate (inconclusive) result. This confirmed previously published findings that T-SPOT.TB has low technical failure results and high diagnostic sensitivity in HIV infected adults and children with active TB.

Commenting on these findings Dr Peter Wrighton-Smith, Chief Executive Officer of Oxford Immunotec said “This study demonstrates that the technical performance of T-SPOT.TB is not affected by the degree of HIV-associated immunosuppression. These results represent a significant advance in the early detection of latent TB infection in immunosuppressed patients, those who are at highest risk of conversion to active disease.”