* Responses to the Mitog en positive control (and occasionally TB Antigen) can be outside the range of the microplate reader. This has no impact on test results. Values >10 IU/ml are reported by the QFT-Plus software as >10 IU/ml. M. tuberculosis infection is not suspected, initially positive results can be confirmed by retesting the original † plasma samples in duplicate in the QFT-Plus ELISA. If repeat testing of one or both replicates is positive, the test result is considered positive. Refer to Guide”, page 58 for possible causes. ‡ “Troubleshooting § In clinical studies, less than 0.25% of subjects had IFN-γ levels of >8.0 IU/ml for the Nil value. TABLE 2. Interpretation criteria for the T-SPOT.TB Test (T-SPOT) Interpretation Nil* TB Response† Mitogen§ Positive¶ spots spots Any ≤10 ≥8 Borderline** spots 5, 6, or 7 spots Any ≤10 Negative†† spots ≤10 ≤4 Indeterminate** >10 spots Any Any spots <5 spots <20 spots ≤10 Source: Based on Oxford Immunotec Limited. T-SPOT.TB [Package insert]. Available at . * The number of spots resulting from incubation of PBMCs in culture media without antigens. The greater number of spots resulting from stimulation of peripheral blood mononuclear cells (PBMCs) † with two separate cocktails of peptides representing early secretory antigenic target-6 (ESAT-6) or culture filtrate protein-10 (CFP-10) minus Nil. § The number of spots resulting from stimulation of PBMCs with mitogen without adjustment for the number of spots resulting from incubation of PBMCs without antigens. ¶ Interpretation indicating that infection is likely. Mycobacterium tuberculosis ** Interpretation indicating an uncertain likelihood of infection. M. tuberculosis Interpretation indicating that infection is not likely. †† M. tuberculosis References:
* Responses to the Mitog en positive control (and occasionally TB Antigen) can be outside the range of the microplate reader. This has no impact on test results. Values >10 IU/ml are reported by the QFT-Plus software as >10 IU/ml. † M. tuberculosis infection is not suspected, initially positive results can be confirmed by retesting the original plasma samples in duplicate in the QFT-Plus ELISA. If repeat testing of one or both replicates is positive, the test result is considered positive. ‡ Refer to “Troubleshooting Guide”, page 58 for possible causes. § In clinical studies, less than 0.25% of subjects had IFN-γ levels of >8.0 IU/ml for the Nil value. TABLE 2. Interpretation criteria for the T-SPOT.TB Test (T-SPOT) Interpretation Nil* TB Response† Mitogen§ Positive¶ ≤10 spots ≥8 spots Any Borderline** ≤10 spots 5, 6, or 7 spots Any Negative†† ≤10 spots ≤4 Indeterminate** >10 spots Any Any ≤10 spots <5 spots <20 spots Source: Based on Oxford Immunotec Limited. T-SPOT.TB [Package insert]. Available at . * The number of spots resulting from incubation of PBMCs in culture media without antigens. † The greater number of spots resulting from stimulation of peripheral blood mononuclear cells (PBMCs) with two separate cocktails of peptides representing early secretory antigenic target-6 (ESAT-6) or culture filtrate protein-10 (CFP-10) minus Nil. § The number of spots resulting from stimulation of PBMCs with mitogen without adjustment for the number of spots resulting from incubation of PBMCs without antigens. ¶ Interpretation indicating that Mycobacterium tuberculosis infection is likely. ** Interpretation indicating an uncertain likelihood of M. tuberculosis infection. †† Interpretation indicating that M. tuberculosis infection is not likely. References:
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