Is IP-10 a Better Biomarker for Active and Latent Tuberculosis in Children than IFNγ?

Background The blood based interferon-gamma release assays (IGRA) for the diagnosis of tuberculosis do not discriminate between active TB disease and latent TB infection (LTBI). The search for distinguishing biomarkers therefore continues, as the accurate diagnosis of tuberculosis is particularly challenging in children. IFN-γ-inducible protein 10 (IP-10/CXCL10) has recently been evaluated as a marker for active TB in adults with promising results. Aim To investigate this new biomarker for active TB and LTBI in paediatrics. Method We measured IP-10 levels using ELISA in supernatants of whole blood samples stimulated with TB-specific-antigens and negative control antigen. Results IP-10 is produced in high levels following mycobacterial antigen stimulation in active TB (n = 17) and LTBI (n = 16) compared to controls (n = 16) and to IFN-γ. The baseline levels of IP-10 are increased in active TB and in LTBI, but there is no significant difference of stimulated levels of IP-10 between active TB and LTBI. Conclusions IP-10 is a biomarker for tuberculosis in children. However like IFNγ, IP-10 also does not distinguish between active TB and LTBI.