TB Accurately Diagnosed by a Single Blood Test

A blood test detects cellular immune responses to proteins specifically associated with tuberculosis (TB) infection.

Called the QuantiFERON-TB Gold In-Tube (QFT), it replaces the original QuantiFERON-TB Gold, and provides the same specificity and accuracy advantages. In addition, the new In-Tube format, already widely used in Europe and Asia, simplifies testing and fits with existing laboratory equipment. The test will replace the tuberculin skin test (TST).

A product of Cellestis (Melbourne, Australia), the QFT gold in-tube system has received the U.S. Food and Drug Administration (FDA; Rockville, MD, USA) approval for use in the United States. CEO of Cellestis, Dr. Tony Radford, commented, "With the In-Tube system, the blood incubation requires virtually no labor and no set-up time. It makes a QFT test as simple as a routine antibody test and extends the availability of QFT testing by streamlining logistics to allow the initial incubation process to be done almost anywhere. The FDA approval now permits our U.S. customers to enjoy the cost-savings, and quality result of In-Tube, as well as a better process fit with hospitals and labs.”

The In-tube format simplifies testing logistics, enabling remote location blood collection. It measures immune responses to peptides that simulate Mycobacteria tuberculosis proteins, which are not present in the BCG vaccine or most non- tuberculosis mycobacteria. Thus, QFT is 99% specific and a positive test result is strongly predictive of true infection with M. tuberculosis. As people suspected of TB infection are normally recommended for TB therapy, which carries risks of liver toxicity and nerve damage, use of the highly specific QFT test will reduce unnecessary therapy and overtreatment, therefore having significant medical benefit.

Over 100 years old, the TST involves a crude tuberculosis extract injected into the skin. Despite its limitations, it is still widely used for detecting TB infection. Significantly, the TST is often confounded in persons vaccinated with Bacillus Calmette-Guerin (BCG) (TB vaccination), as well as those exposed to certain environmental bacteria, giving many people false-positive TST results. The TST has poor reproducibility and requires two patient encounters; one to inject the subject and a second, two to three days later, to read the inflammation it may produce. Measuring the inflammation requires trained medical personnel but is still highly subjective, and is notorious for inaccuracy. This leads to poor use of valuable medical resources, and the need for a second clinic visit means many people fail to have their TST read.

QFT provides a new standard for TB control and gives the US TB control community an effective, reliable, and accurate screening method. In addition, QFT yields dramatic cost savings in medical staff time and by eliminating the common false-positive results of the TST. For TB control programs across the nation, QFT can relieve the medical, logistic, administrative, and cost burden associated with TB testing compliance.

Cellestis is a listed Australian biotechnology company commercializing QuantiFERON technology for diagnosing TB and other diseases worldwide. QuantiFERON-TB Gold tests for the presence or absence of a protein (gamma- interferon) produced by a patient's white blood cells after stimulation with specific TB proteins. The test has received regulatory and policy approvals in the United States, Japan, Europe, and elsewhere.


Related Links:
Cellestis
U.S. Food and Drug Administration