1 mL into each of 3 Cellestis QuantiFERON Gold-in tube collection tubes supplied by ADx.
Tubes must be drawn in the following order:
1. GRAY top tube
2. RED top tube
3. PURPLE top tube
Draw 1 ml into each tube and fill exactly up to the black line. **DO NOT OVERFILL OR UNDERFILL TUBES**. Immediately after filling tubes, shake firmly 10 times to ensure that the tube surface is coated with blood. **Avoid shaking too vigorously which could cause gel disruption.** Label each of the three tubes and include the time of collection. Maintain tubes at ambient temperature.
Do NOT centrifuge! Keep at room temperature (18-22°C).
1 mL in each of three Cellestis QuantiFERON Gold in tube collection tubes supplied by ADx.
Improperly filled tubes, frozen or centrifuged specimens.
Place all three tubes in one biohazard bag and send at ambient (17-25°C) temperature in a well insulated container to reach the laboratory within 16 hours of draw. When shipping, send ambient whole blood Priority Overnight via FedEx and in a well insulated container.
Stable at room temperature (18-22°C) for a maximum of 16 hours following draw.
If other blood work is requested, please collect the QuantiFERON In-Tubes LAST.
If a butterfly is used, use a purge (throw away) tube so the tubing does not take up any of the required 1 mL volume in the first tube.
Lymphocyte stimulation followed by ELISA
Immunology Lab - Functional Assay
Assessement of exposure to M. tuberculosis.
The QuantiFERON®-TB Gold In-Tube (QFT) test is based on the measurement of a cell mediated response to M. tuberculosis-specific antigens (ESAT-6, CFP-10 and TB7.7). Whole blood is stimulated with these antigens for 16-24 hours, following which interferon gamma (IFNg) is measured in the plasma using ELISA methodology. Controls include unstimulated cells (Nil control) and phytohemagglutinin stimulated cells (Mitogen control). A test is considered positive when IFNg released in response to TB antigens is significantly greater than the Nil control (TB-Nil), and the Mitogen control has a robust IFNg response. The QFT result is indeterminate if the Nil control is high (>0.8 IU/mL) or the mitogen control is low (< 0.5 IU/mL). Although the test is reported qualitatively, IFNg levels for the individual test conditions are also reported as recommended by the Centers for Disease Control and Prevention1.
The QFT detects infections due to M. tuberculosis complex (M. tuberculosis, M. bovis and M. africanum). BCG strains and non-tuberculous mycobacteria do not express ESAT-6, CFP-10 and TB7.7 proteins. Therefore, patients either vaccinated with BCG or infected with non-tuberculous mycobacterial strains should test negative.
QFT results should always be interpreted in conjunction with clinical and other relevant laboratory findings.
1 Guidelines for Using the QuantiFERON®-TB Gold Test for Detecting Mycobacterium tuberculosis Infection, United States. Centers for Disease Control and Prevention. Morbidity and Mortality Weekly Report (MMWR). December 16, 2005 / 54(RR15);49-55