Blood-based biomarkers allow better TB diagnosis and observance
Latent TB infections (LTBI) often precede ATB, and patients with LTBI are at 20 times greater risk of developing ATB.
The researchers conducted a study with three groups of people located in the area around metro Atlanta. One group had asymptomatic LTBI, another had un-treated ATB, and others were undergoing ATB treatment. Results showed that Mtb-specific CD4 T-cells' frequencies had certain immune markers: HLA-DR, CD38, and Ki-67. These markers identified ATB patients with more than 96 percent sensitivity and 100 percent accuracy. The markers showed which people had untreated ATB and which people had finished their anti-TB treatments.
TB is a continued global health concern. Experts estimate that in 2013, 9 million people contracted ATB in 2013 and 1.5 million of those people died from TB.
"In order to reduce the burden of TB globally, identifying and treating all TB cases is a critical priority," Emory University School of Medicine professor Jyothi Rengarajan said. "However, accurate diagnosis of active TB disease remains challenging and methods for monitoring how well a patient responds to the six-to nine-month long, four-drug regimen of anti-TB treatment, are highly inadequate.
Rengarajan said their findings show that blood-based biomarkers have the potential to accurately diagnose ATB and discriminate between ATB and LTBI.
"We are now interested in evaluating these biomarkers in larger studies in TB-endemic areas and across a roader spectrum of Mtb infection, including extra-pulmonary TB and in HIV-infected populations," Rengarajn said. "Blood-based biomarkers will be particularly useful in situations where sputum-based diagnosis of TB is more difficult. Because these biomarkers provide a gauge of Mtb load within individuals, they could also have utility as surrogate markers of treatment response and as predictors of treatment efficacy, cure and relapse in patients undergoing treatment for drug-susceptible as well as drug-resistant TB."
More details are available in the Journal of Clinical Investigation, which was published online Monday.