_Why offer COVID-19 T cell testing?_
Performance of the T-SPOT.COVID test
|Time after positive PCR results||T-SPOT.COVID|
|< 60 days||96.6% (84/87)||–|
|> 60 days||83.3% (40/48)||–|
- Positive agreement: 135 individuals with a previous positive COVID-19 test result
- Negative agreement: 98 individuals at low risk of acquiring infection and who have never had a positive COVID-19 test result
- How does the T-SPOT technology work?
Our T-SPOT.COVID test based on ELISPOT technology is normalised for both cell number and culture conditions. This means that the test standardises the number of cells and removes serum factors that could adversely affect results, making it the most sensitive and specific test for T cell measurement. A blood sample is collected using routine phlebotomy and a standard blood collection tube from which a subset of white blood cells, known as peripheral blood mononuclear cells (PBMCs), are isolated. The cells are washed, counted and normalised to create a standard cell suspension. A standard number of cells are added into specially designed plates and stimulated with antigens specific to the disease under study. Cells responding to these antigens release a chemical messenger known as a cytokine. Cytokine antibodies are used to directly capture the cytokine as it is released by the cells. A secondary labelled antibody is added and binds to the captured cytokine. A detection reagent is added and reacts with the secondary labelled antibody. This reaction produces spots, which are a footprint of where the cytokine was released. Spots are then enumerated.
- What does a positive T-SPOT.COVID test result mean?
A positive test result means that the patient has T cells that are reactive to the SARS-CoV-2 specific peptides used in the T-SPOT.COVID test. It is highly likely that they have been exposed to the SARS-CoV-2 virus.
- What does a negative test result mean?
A negative test result means that the patient does not have T cells that are reactive to the SARS-CoV-2 specific peptides used in the test. It is therefore unlikely that they have been exposed to the SARS-CoV-2 virus.
- What regulatory approval does the T-SPOT.COVID test have?
The T-SPOT.COVID test is CE marked and has been submitted to the FDA for Emergency use authorisation.
- T-SPOT.COVID Package Insert: T-SPOT.COVID-PI-UK-0001
- Wyllie D, Mulchandani R, Jones HE et al. SARS-CoV-2 Reactive T cell numbers are associated with protection from COVID-19: A prospective cohort study. medRxiv. doi: 10.11012020.11.02.20222778