T-Spot.TB

Also known as: TB ELISpot

This is a T cell based assay for the detection of infection with Mycobacterium tuberculosis. T-SPOT.TB enumerates individual activated TB-specific effector T cells. T-SPOT.TB assay cannot distinguish between latent and active TB infection.

This test may be appropriate in the following situations:

• For detection of latent TB in people whose Mantoux testing shows positive results, or in people for whom Mantoux testing may be less reliable, for example BCG-vaccinated people.
• For new entrants from high-incidence countries
• For contact tracing in a TB outbreak
• For people with HIV and other people who are immunocompromised
• For healthcare workers who have recently arrived from high-incidence countries or who have had contact with patients in settings where TB is highly prevalent
• For detection of latent TB in patients prior to anti-TNF-α treatment such as infliximab, etanercept etc.

For detailed recommendations please see NICE clinical guideline 117 (CG117), issued March 2011 (http://www.nice.org.uk/guidance/cg117).

Specimen requirements

Heparinised blood samples are required. Optimal blood volumes are:

1. 8 mL for an adult and children over 10 years
2. 6 mL for a child between 2-10 years
3. 2 mL for infants up to 2years
4. Larger volumes of blood may be required for lymphopaenic patients
5. 16 mL of heparin is recommended for patients with HIV

Sample should be taken on Monday-Thursday and must be received in the Immunology Laboratory within 8 hours of venepuncture and before 3pm. Samples must not have been refrigerated or centrifuged.

Cost

Price on application

Laboratory turnaround time

3 working days

Laboratory method

N/A

Reference range/units

N/A

Associated tests

Quantiferon TB Gold

Shipping and storage

See specimen requirements

Further information and contact details

For further information, email immunology.office@nhs.net