Specimen Requirements

Preparation of Patient: 

None

Specimen Type:

Lithium heparin plasma from whole blood samples

Container Type: 

QIAGEN QuantiFERON®-TB Gold Plus (QFT-Plus) Blood Collection Tubes (4 tubes: NIL (grey), TB1 (green), TB2 (yellow) and Mitogen (lavender)).

LIS Container Code = QL, QGY, QGN, QYL

Specimen Volume: 

1mL whole blood in each tube (0.8-1.2 mL).  Fill volume must fall within the black fill mark on the side of the tube

Specimen Handling/Transport:

Incubate and centrifuge before transport.  Transport at room temp

Special Handling Instructions: 

1. Label tubes appropriately.  Make sure each tube (Nil, TB1, TB2 and Mitogen) is identifiable by its label or other means once the cap is removed. It is recommended to record the time and date of blood collection.  Important: QFT-Plus Blood Collection Tubes should be at room temperature 17–25°C at the time of blood collection
2. For each patient, collect 1 ml of blood by venipuncture directly into each of the QFT-Plus Blood Collection Tubes. This procedure should be performed by a trained phlebotomist.
   1. As 1 ml tubes draw blood relatively slowly, keep the tube on the needle for 2–3 seconds once the tube appears to have completed filling. This will ensure that the correct volume is drawn.
   2. The black mark on the side of the tubes indicates the validated range of 0.8 to 1.2 ml. If the level of blood in any tube is outside of the indicator mark, a new blood sample should be obtained. Under- or over-filling of the tubes outside of the 0.8 to 1.2 ml range may lead to erroneous results.
   3. If a “butterfly needle” is being used to collect blood, a “purge” tube should be used to ensure that the tubing is filled with blood prior to the QFT-Plus Blood Collection tubes being used.
3. Immediately after filling the tubes, shake them ten (10) times just firmly enough to make sure the entire inner surface of the tube is coated with blood. This will dissolve antigen on the tube walls.  Important: Over vigorous shaking may cause gel disruption and could lead to aberrant results.
4. Following labeling, filling and shaking, the tubes must be transferred to a 37°C ± 1°C incubator as soon as possible, and within 16 hours of collection. Prior to incubation, maintain tubes at room temperature (17–25°C). If QFT-Plus Blood Collection Tubes are not incubated at 37°C directly after blood collection and shaking, invert the tubes to mix 10 times prior to incubation at 37°C.
5. Incubate the QFT-Plus Blood Collection Tubes UPRIGHT at 37°C ± 1°C for 16 to 24 hours
6. After incubation, blood collection tubes may be held between 4°C to 27°C for up to 3 days prior to centrifugation
7. After incubation of the tubes at 37°C ± 1°C, centrifuge the tubes for 15 minutes at 2000 to 3000 RCF (g). The gel plug will separate the cells from the plasma. If this does not occur, the tubes should be re-centrifuged.  After centrifugation, take care not to disturb material on the surface of the gel.

Specimen Stability/Storage:

Once processed, uncentrifuged samples are stable 3 days at 4-27°C.  Once centrifuged, plasma is stable for 5 days at 2-8°C.