Blood-based biomarkers located on Mycobacterium tuberculosis-specific CD4 T-cells discriminated between pulmonary active tuberculosis and latent infections, according to recently published data.
“In order to reduce the burden of TB globally, identifying and treating all TB cases is a critical priority,” Jyothi Rengarajan, PhD, of Emory University School of Medicine and Emory Vaccine Center, said in a press release. “However, accurate diagnosis of active TB disease remains challenging and methods for monitoring how well a patient responds to the 6- to 9-monthlong, four-drug regimen of anti-TB treatment, are highly inadequate.”
Rengarajan and colleagues evaluated the expression of immune activation markers on Mtb-specific CD4 T-cells using polychromatic flow cytometry. Participants were HIV-negative adults with active TB or latent M. tuberculosis infection (LTBI) from Georgia (n = 51) and South Africa (n = 36). Participant diagnosis was confirmed with sputum acid-fast bacilli smear microscopy, with an amplified M. tuberculosis test performed for direct detection performed upon positive diagnosis.
Frequencies of M. tuberculosis-specific CD4 T-cells expressing immune markers CD38, HLA-DR and Ki-67 were higher in participants with active TB than in those with LTBI. Measuring these frequencies identified active TB patients with 100% specificity and greater than 96% sensitivity, the researchers wrote, and also were capable of distinguishing participants with untreated active TB from those who had successfully completed anti-TB treatment.
“Our findings show that blood-based biomarkers have the potential to accurately diagnose [active TB] and discriminate between [active TB] and LTBI,” Rengarajan said in the release. “Because these biomarkers provide a gauge of [M. tuberculosis] 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.”
Disclosure: Adekambi, Rengarajan and another researcher report being inventors on a patent application related to this work.