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QuantiFERON-TB Gold In-Tube

Applications and Keys to Accurate Performance


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Interferon Gamma Release Assays (IGRA): An Alternative to TST?

Slide 5

November 2009

Probably the most successful and well-studied approach have been the interferon gamma release assays. The general principle behind IGRAs is the measurement of in vitro levels of interferon gamma produced by sensitized T cells that have been stimulated by purified or synthesized TB antigens. In the first step, blood is collected and mixed with TB-specific antigens. The tubes are then incubated at 37°C for generally 16 to 24 hours. During this incubation period, antigen presenting cells process the purified TB antigens. Following processing, the antigen presenting cell then distributes the antigen on its surface for recognition by an antigen-specific T cell. If an individual has been exposed to TB in the past, the primed or sensitized T cell will then produce and release interferon gamma in response to binding to the antigen presenting cell. Following the incubation period, the tubes are centrifuged to separate the plasma and cell layers. And finally, the tubes are sent to a clinical laboratory where the levels of interferon gamma are measured by an ELISA-based assay.

IGRA: An Alternative to TST?


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