Quantiferon (Gamma Interferon For TB)

Immunology

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Description

QuantiFERON�-TB Gold is an indirect test for latent M. tuberculosis infection ( LTBI ) and M. tuberculosis complex infection. Tuberculosis is a communicable disease caused by infection with M. tuberculosis complex organisms ( M. tuberculosis, M. bovis, M. africanum ), which typically spreads to new hosts via airborne droplets from patients with respiratory tuberculosis disease. A newly infected individual can become ill from tuberculosis within weeks to months, but most infected individuals remain well. Latent tuberculosis infection ( LTBI ), a non-communicable asymptomatic condition, persists in some, who might develop tuberculosis disease months or years later. The main purpose of diagnosing LTBI is to consider medical treatment for preventing the development of tuberculosis disease. Until recently the tuberculin skin test ( TST ) was the only available method for diagnosing LTBI. Cutaneous sensitivity to tuberculin develops from 2-10 weeks after infection. However, some infected individuals, including those with a wide range of conditions hindering immune functions, but also others without these conditions, do not respond to tuberculin. Conversely, some individuals who are unlikely to have M. tuberculosis infection exhibit sensitivity to tuberculin and have positive TST results after vaccination with bacille Calmette-Guerin ( BCG ), infection with mycobacteria other than M. tuberculosis complex, or undetermined other factors.

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Indications

TB, Latent TB.

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Sample Type

Quantiferon bottles ( set of four ) available from Laboratory Medicine reception at NGH, For RHH tubes can be obtained from C floor phlebotomy 07:30 to 17:15 Monday to Friday, outside these hours tubes can be obtained from Clinical Chemistry RHH. Ensure the tubes are filled to the collection line ( approx. 1mL -DO NOT overfill ) and adequately mix each tube after collection. Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier. Samples should arrive within 16 hours of venesection unless the laboratory is incubating and separating the samples locally.

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Reference Range

Negative is normal.

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Turnaround Time

Within 5 days

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Testing Frequency

Weekly

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External Notes

Four vacutainer type bottles colour coded grey, green, yellow and purple should be obtained from Laboratory Medicine reception NGH or C floor phlebotomy/Clinical Chemistry RHH and filled with blood up to the black line ( approx 1ml ). The tube should not be overfilled. After blood sampling all tubes should be shaken at least 10 times. The Quantiferon test is performed in Immunology NGH.

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References

Kang YA, et al. Discrepancy between the tuberculin skin test and the whole-blood interferon gamma assay for the diagnosis of latent tuberculosis infection in an intermediate tuberculosis-burden country. JAMA. 2005. 293: 2756-2761.Whalen CC. Diagnosis of latent tuberculosis infection: measure for measure. JAMA. 2005. 293:2785-2787.Mori T, et al. Specific detection of tuberculosis infection: An interferon-y-based assay using new antigens. Am J Respir Crit Care Med. 2004. 170:59-64.Pai M, et al. Interferon-y assays in the immunodiagnosis of tuberculosis: a systematic review. Lancet Infect Dis. 2004. 4:761-776.Munk ME, et al. Use of ESAT-6 and CFP-10 antigens for diagnosis of extrapulmonary tuberculosis. J Infect Dis. 2001.183:175-176.Andersen P, et al. Specific immune-based diagnosis of tuberculosis. Lancet. 2000. 356:1099-1104.

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Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.