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Results Line and Enquiries

0203 313 5353


Category Immunology
Test background

This assay detects interferon-gamma (IFN-γ) secretion from peripheral blood mononuclear cells in response to stimulation with Mycobacterium tuberculosis antigens (ESAT6, CFP10). This test cannot differentiate between latent tuberculosis infection (LTBI) and tuberculosis (TB) disease.

The negative predictive value of this test for TB infection is reported to be 98%.

Clinical Indications

Latent TB infection
Screening for latent TB before administration of certain biologics (e.g. anti-TNF drugs)

Reference range


Sample & container required 10 mL heparin (green top);
Samples must be received in the laboratory (Charing Cross) by 2pm Monday to Friday for the test to be performed.
Sample volume See above
Turnaround time 4 days

The lab is in the process of introducing an automated TB Elispot method which may be used for lymphocyte isolation/counting and which is not currently accredited.