In the study referred to above, a combined readout of IFN-g and IP-10 is more sensitive than IFN-g alone. The combined readout should be evaluated prospectively in large, unselected populations, including children and HIV co-infected patients. For accurate and reliable diagnostic performance, it should include significant numbers of cases with co-existing HIV infection.
The interferon gamma release assay detects tuberculosis by detecting in vitro production of interferon-gamma by T cells. This test is useful for both active and latent tuberculosis. While TB can be asymptomatic, it is contagious and can be transmitted to others by coughing.
The QuantiFERON-TB test is a third-generation interferon-gamma test. It measures the interferon-gamma level in whole blood. The results are expressed as IFN-g per millimeter of blood. This test is more sensitive than the ELISA test and does not boost anamnestic immune responses. But what's the difference between the two tests?
The detection of IFN-g is not a simple task. There are many methods to measure interferon-gamma in human samples. Conventional methods such as enzyme-linked immunosorbent assays are time-consuming and have low sensitivity and cannot differentiate different stages of TB disease. Electrochemical biosensor systems have been reported to detect interferon-gamma. Besides, an ELISA washer is a helpful device. It is mainly used to clean some residual substances after the detection of the ELISA plate, so as to reduce the errors caused by the residues in the subsequent detection process.
To determine IFN-gamma levels, whole blood samples are mixed with synthetic peptides (QFT-G) representing two M. tuberculosis proteins, CFP-10 and ESAT-6. After this incubation period, the interferon-gamma level is measured. IFN-gamma is a cytokine produced by white blood cells in response to antigens. The amount of IFN-gamma in the samples will indicate whether the blood contains the antigens.
The TS-SPOT assay detects IFN-g responses in different forms of TB. The TS-SPOT assay is sensitive, and the results are accurate within a few days. TS-SPOT is a useful adjunct to current tests. In addition, it is cost-effective. So, if you're worried about TB, use it to diagnose your patients.
The QuantiFERON-TB Gold test has been recommended by the Centers for Disease Control and Prevention (CDC). However, some studies have shown that the results of the two tests may not be compatible. The cutoff level for the QuantiFERON-TB Gold kit is 0.35 IU/ml. This cutoff is more likely to yield inconsistent results when the levels are borderline between the recommended threshold.
The Quantiferon TB Gold In Tube test has high specificity in low-risk individuals and high sensitivity in those with active disease. The study analyzed two cohort studies involving more than one thousand individuals. It is widely available in public health laboratories, hospitals, and commercial testing centers. Its sensitivity and specificity are comparable to other IFN-g tests. The results were interpreted according to the stricter definitions used by the manufacturers.
The Quantiferon-tb gold in-tube collection system is FDA approved. It consists of three tubes with peptide cocktails that simulate esat-6, cfp-10, and tb 7.7 (p4) proteins. The peptides stimulate the immune response in heparinized whole blood, and the quantiferon-y assay detects the presence of these antibodies in the sample.