QuantiFERON-TB Gold Plus (QFT-Plus)

• High sensitivity and high specificity for accurate TB infection detection 
• Exclusive TB-specific antigens to elicit both CD4 and CD8 T-cell responses
• Unaffected by BCG vaccination
• Innovative CD8 T-cell technology
• Appropriate for all at-risk populations, including children, pregnant women and immunocompromised patients 
• Referenced in >2500 published studies on TB testing

QuantiFERON-TB Gold Plus (QFT-Plus) assesses the cell-mediated immune (CMI) response to TB-specific ESAT-6 and CFP-10 antigens through a quantitative measurement of IFN-γ in a whole blood sample. 

QFT-Plus is an indirect test for M. tuberculosis infection (including disease) and is intended for use in conjunction with risk assessment, radiography, and other medical and diagnostic evaluations. 

QFT-Plus uses exclusive TB-specific antigens that elicit CD4 and CD8 T-cell responses.  

TB-specific CD8 T cells have been:

• Detected more frequently in those with active TB disease vs TB infection
• Associated with recent exposure to TB
• Detectable in active TB subjects with HIV co-infection and in young children

Testing with QFT-Plus is performed in two steps. First, whole blood samples are collected and exposed to the TB-specific or control antigens in the four custom QFT-Plus Blood Collection Tubes. Second, the production of IFN-γ in response to these antigens is measured using an enzyme-linked immunoassay (ELISA) or chemiluminescence immunoassay (CLIA). 

QuantiFERON-TB Gold Plus has 97.27% test specificity and 94.09% test sensitivity. 

For additional details and performance characteristics, refer to the QuantiFERON-TB Gold Plus ELISA Instructions for Use. 

QuantiFERON is a powerful Premolecular diagnostic technology that delivers results with high sensitivity, enabling the detection of M. tuberculosis infection even in early or latent stages. Premolecular Diagnostics that employ QuantiFERON technology, like QFT-Plus, are able to detect infection at an earlier stage than is possible with DNA- and RNA-based molecular diagnostics.

QFT-Plus results are interpreted based on the IFN-γ values in each of the four QFT-Plus Blood Collection Tubes:

TB1 – primarily detects CD4 T-cell response

TB2 – optimized for detection of CD4 and CD8 T-cell responses

Mitogen – positive control; low response may indicate inability to generate IFN-γ

Nil – negative control; adjusts for background IFN-γ

The QFT-Plus test is a straightforward laboratory TB blood test that involves the following steps: 

1. Collect whole blood into the QFT-Plus Blood Collection Tubes, using one of two options: 
   Direct draw: Collect 1 mL of whole blood directly into each of four QFT-Plus Blood Collection Tubes and hold at room temperature for up to 16 hours prior to incubation. 
   Single lithium-heparin or sodium-heparin tube: Draw at least 5 mL of blood into a single blood collection tube containing lithium- or sodium-heparin as the anticoagulant. Blood collected into a single lithium- or sodium-heparin tube may be stored at room temperature or refrigerated for up to 53 hours prior to transfer to QFT-Plus tubes and incubation.
2. Incubate samples in the QFT-Plus Blood Collection Tubes for 16 to 24 hours at 37°C.
3. Detect released IFN-γ in harvested plasma using the QuantiFERON-TB Gold Plus ELISA test.
4. Analyze results using optional QFT-Plus Analysis Software.

Refer to the QuantiFERON-TB Gold Plus Blood Collection Tubes and ELISA Instructions for Use for detailed instructions for use. 

Automated QuantiFERON TB testing using CLIA technology is also available using the LIAISON QuantiFERON-TB Gold Plus test. 

QFT-Plus can be used in many clinical and public health settings to screen for TB infection in people at risk. Risk groups described by the WHO and the US CDC include healthcare workers, children, people who are immunocompromised, immigrants, military personnel and those living or working in congregate settings like correctional facilities.