2. Interpretation Criteria for the T-SPOT.TB Test
View in chapter → Interferon-y Release Assays (IGRAs)
Last Updated April 2026
| Nil | ≤ 10 spots |
|---|---|
| TB Response | ≥ 8 spots |
| Mitogen | Any |
| Nil | < 10 spots |
|---|---|
| TB Response | 5, 6, or 7 spots |
| Mitogen | Any |
| Nil | ≤ 10 spots |
|---|---|
| TB Response | > 20 spots |
| Mitogen | > 20 spots |
| Nil | ≤ 10 spots | ≤ 10 spots |
|---|---|---|
| TB Response | Any | < 5 spots |
| Mitogen | Any | < 20 spots |
Source: Based on Oxford Immunotec T-Spot.TB package insert.
Available at:
http://www.oxfordimmunotec.com/international/wp-content/uploads/sites/3/Final-File-PI-TB-US-V6.pdf
1. Interpretation indicating that Mycobacterium tuberculosis infection
is likely.
2. Interpretation indicating an uncertain likelihood of M. tuberculosis
infection. In the case of Invalid results, these should be reported as
“Invalid” and it is recommended to collect another sample and retest the
individual.
3. Interpretation indicating that M. tuberculosis infection is not
likely.