Text Equivalent - Appendix D
Figure 1. Algorithm for interpretation of T-SPOT®.TB assays
This figure is an algorithm for interpreting T-SPOT. TB results. Additional information is available from the package insert (download from www.oxfordimmunotec.com).
Step 1: Count Nil Control Spots
Where more than 10 spots are seen, the result should be considered "Indeterminate Footnote A".
Step 2: Count Positive Control Spots
The Positive Control spot count should be greater than or equal to 20 or show saturation (too many spots to count). Where the Positive Control spot count is less than 20 spots, the result should be considered 'Indeterminate Footnote A', unless either Panel A or Panel B are 'Reactive' as described in results interpretation (see below), in which case the result is valid.
Step 3: Count Panel A and Panel B Spots
Step 4: Interpret Results
Reactive (Positive) T-SPOT
- Nil Control spot count is zero to five spots and (Panel A or Panel B spot count) minus (Nil Control spot count) is greater than or equal to six spots OR
- Nil Control spot count is six to 10 spots and (Panel A or Panel B spot count) is equal to or greater than two times (Nil Control spot count)
Non-Reactive (Negative) T-SPOT
- Reactive test criteria (above) are not met and the Positive Control is valid (i.e., greater than or equal to 20 spots or saturation)
Borderline (Indeterminate) Footnote B T-SPOT
- Nil Control spot count is zero to five spots and (Panel A or Panel B spot count) minus (Nil Control spot count) equals five to seven spots
- Figure 1 - Footnote A
- Refer to the T-SPOT®.TB Technical Handbook for possible causes (may be downloaded from Oxford Immunotec
). It may be necessary to collect a further sample and re-test the individual. - Figure 1 - Footnote B
- Result should be considered in conjunction with all available clinical information. It may be necessary to collect a further sample and re-test the individual.
Refer to the T-SPOT®.TB Technical Handbook for possible causes (download from www.oxfordimmunotec.com). It may be necessary to collect a further sample and re-test the individual.