T-SPOT is an assay used for tuberculosis diagnosis. It which belongs to the group of interferon-gamma release assays. The test is manufactured by Oxford Immunotec in the UK.and it counts the number of anti-mycobacterial effector T cells, white blood cells that produce interferon-gamma, in a sample of blood. This gives an overall measurement of the host immune response against mycobacteria, which can reveal the presence of infection with Mycobacterium tuberculosis, the causative agent of tuberculosis (TB).
The important question is how it compares to the simple and widely available skin tuberculin test. Initial studies indicated a sensitivity of 97.2%. However, more recent data from a study in children with active TB disease in the UK suggest that the sensitivity of the T-SPOT.TB may in fact be worse than that of the tuberculin skin test (sensitivity reported as 66% and 82%, respectively)..A metaanalysis of studies in children with active tuberculosis published in 2011 suggests that the sensitivity of the T-SPOT.TB is very similar(but not superior) to that of the tuberculin skin test (pooled sensitivity reported as 84% and 80%, respectively).
Although superiority to skin tubeculin test is not yet established, FDA approved IGRAS test and T0SPot blood tests and the CDC guideline recommends their use. “….. TSTs and IGRAs (QFT-G, QFT-GIT, and T-Spot) may be used as aids in diagnosing M. tuberculosis infection,” the guidelines authors write. “They may be used for surveillance purposes and to identify persons likely to benefit from treatment. Multiple additional recommendations are provided that address quality control, test selection, and medical management after testing.”
As such, this is an FDA approved test but the reliable evidence shows that the expert consensus is that the farther clinical studies are still required. Prospective Comparison of the Tuberculin Skin Test and Interferon-Gamma Release Assays in Diagnosing Infection With Mycobacterium Tuberculosis and in Predicting Progression to Tuberculosis, NCT01622140.
Bamford, A. R J; Crook, A. M; Clark, J. E; Nademi, Z.; Dixon, G.; Paton, J. Y; Riddell, A.; Drobniewski, F. et al. (2009). Comparison of interferon- release assays and tuberculin skin test in predicting active tuberculosis (TB) in children in the UK: A paediatric TB network study”. Archives of Disease in Childhood 95 (3): 1806.
Ritz, Nicole; Connell, Tom G.; Paxton, Georgia A.; Buttery, Jim P.; Curtis, Nigel; Ranganathan, Sarath C. (2008). “A Three-Way Comparison of Tuberculin Skin Testing, QuantiFERON-TB Gold and T-SPOT.TB in Children”. In Dheda, Keertan. PLoS ONE 3 (7): e2624.
Connell, Thomas G.; Tebruegge, Marc; Ritz, Nicole; Bryant, Penelope A.; Leslie, David; Curtis, Nigel (2010). “Indeterminate Interferon- Release Assay Results in Children”. The Pediatric Infectious Disease Journal 29 (3): 2856.
Jump up ^ Connell, T. G.; Tebruegge, M.; Ritz, N.; Bryant, P.; Curtis, N. (2010). “The potential danger of a solely interferon- release assay-based approach to testing for latent Mycobacterium tuberculosis infection in children”. Thorax 66 (3): 2634
Mandalakas, A. M.; Detjen, A. K.; Hesseling, A. C.; Benedetti, A.; Menzies, D. (2011). “Interferon-gamma release assays and childhood tuberculosis: Systematic review and meta-analysis”. The International Journal of Tuberculosis and Lung Disease 15 (8): 101832.