A specific collection tube kit is required for this test. The kit consists of four Quantiferon Gold tubes labelled TB1 (green), TB2 (yellow), MITOGEN (pink) AND NIL (grey). All four tubes MUST BE COLLECTED. Each tube will draw 1mL of blood.
NOTE: 1mL draw tubes will fill very slowly. Collectors should wait 2-3 seconds once the tube appears filled before removing the tube from the needle. If a butterfly needle is used, first collect other required tubes or use a "purge" tube to remove air from the line and then p[roceed with collecting the Quantiferon Gold tubes. A black mark on the side of tube indicates the 1mL fill line. Tubes are validated for volumes 0.8 - 1.2 mL. The acceptable fill range is the total width of the black band. See tube image for graphic representation. If the volume of blood collected in any tube is not within this range it is recommended to obtain another blood sample.
Once collected, the tubes SHOULD BE SHAKEN VIGOROUSLY (frothing is OK). Blood samples must be received by our laboratory WITHIN 16 HOURS of collection hence the specimen needs to be sent to Mater Central Specimen Reception with the next available courier.
MBS Item 69471: Test of cell-mediated immunity in blood for the detection of latent tuberculosis in an immunosuppressed or immunocompromised patient. To satisfy this condition and when applicable, "immunosuppressed patient" or "immunocompromised patient" must be noted on the request form.
The immune response to infection with Mycobacterium tuberculosis is predominantly a Cell Mediated Immune (CMI) response and results in sensitization of T-cell lymphocytes specific to M.tuberculosis antigens, which circulate in the blood. Interferon-ã (IFN-ã) is a protein produced by sensitized T-cells (primarily CD4 but also CD8) upon stimulation with their specific antigen. The QuantiFERON-TB assay detects CMI responses to tuberculosis infection by measuring IFN-ã produced in whole blood after incubation with tuberculin purified protein derivative (PPD).
"The Interferon Gamma Assay (Quantiferon) was comparable with the Tuberculin Skin Test in its ability to detect latent tuberculosis infection. It was less affected by prior BCG vaccination, discriminated responses due to non-tuberculosis mycobacteria and avoided variability and subjectivity associated with performing and reading a skin test." (Mazurek et all JAMA 2001,268:1740)