What is this test?
T-SPOT.TB measures the response of immune cells to specific proteins of Mycobacterium tuberculosis. It indicates whether the immune system has likely encountered the causative agent.
Why might it be ordered?
- To check for tuberculosis infection after contact or at increased risk.
- Before certain drugs that suppress the immune system, or as part of an evaluation for tuberculosis.
What sample is needed?
Venous blood is taken in special tubes. Cells must be processed within the specified time, so sampling is coordinated with the laboratory.
How should you prepare?
Fasting is usually not required. Report medicines or conditions that suppress the immune system and any recent severe infection.
How should you understand the result?
A positive result supports tuberculosis infection but does not distinguish latent infection from active disease. A negative result does not completely exclude infection in someone with suppressed immunity or very recent exposure.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.
- Laboratory Tests — MedlinePlus, U.S. National Library of Medicine
- How to Prepare for a Lab Test — MedlinePlus, U.S. National Library of Medicine
- How to Understand Your Lab Results — MedlinePlus, U.S. National Library of Medicine
- Antibody Serology Tests — MedlinePlus, U.S. National Library of Medicine