Utility of Host Markers Detected in Quantiferon Supernatants for the Diagnosis of Tuberculosis in Children in a High-Burden Setting

Novel N Chegou,Anneke C Hesseling,Gerhard Walzl,Elisabetta Walters,Anne K Detjen,Lani Thiart,Anna M Mandalakas,Madhukar Pai

doi:10.1371/journal.pone.0064226

Abstract

BackgroundThe diagnosis of childhood tuberculosis (TB) disease remains a challenge especially in young and HIV-infected children. Recent studies have identified potential host markers which, when measured in Quantiferon (QFT-IT) supernatants, show promise in discriminating between Mycobacterium tuberculosis (M.tb) infection states. In this study, the utility of such markers was investigated in children screened for TB in a setting with high TB incidence.Methodology and Principal Findings76 children (29% HIV-infected) with or without active TB provided blood specimens collected directly into QFT-IT tubes. After overnight incubation, culture supernatants were harvested, aliquoted and frozen for future immunological research purposes. Subsequently, the levels of 12 host markers previously identified as potential TB diagnostic markers were evaluated in these supernatants for their ability to discriminate between M.tb infection and disease states using the Luminex platform. Of the 76 children included, 19 (25%) had culture confirmed TB disease; 26 (46%) of the 57 without TB had positive markers of M.tb infection defined by a positive QFT-IT test. The potentially most useful analytes for diagnosing TB disease included IFN-α2, IL-1Ra, sCD40L and VEGF and the most useful markers for discriminating between QFT-IT positive children as TB or latent infection included IL-1Ra, IP-10 and VEGF. When markers were used in combinations of four, 84% of all children were accurately classified into their respective groups (TB disease or no TB), after leave-one-out cross validation.ConclusionsMeasurement of the levels of IFN-α2, IL-1Ra, sCD40L, IP-10 and VEGF in QFT-IT supernatants may be a useful method for diagnosing TB disease and differentiating between active TB disease and M.tb infection in children. Our observations warrant further investigation in larger well-characterized clinical cohorts.

Highlights

Tuberculosis (TB) remains a global health problem and the diagnosis remains challenging especially in children, who typically develop paucibacillary disease [1]
Measurement of the levels of IFN-a2, interleukin-1 receptor antagonist (IL-1Ra), soluble CD40 ligand (sCD40L), inducing protein (IP)-10 and vascular endothelial growth factor (VEGF) in Quantiferon TB Gold In-Tube assay (QFT-IT) supernatants may be a useful method for diagnosing TB disease and differentiating between active TB disease and M.tb infection in children
When the TB antigen-specific marker responses were calculated by subtraction of the respective unstimulated control levels, only the median levels of VEGF and IFN-c were significantly different between the TB and non-TB groups, with the levels of sCD40L showing a trend towards significance (0.05,p#0.08) (Table 2)

Summary

Introduction

Tuberculosis (TB) remains a global health problem and the diagnosis remains challenging especially in children, who typically develop paucibacillary disease [1]. There is a need for new, rapid and accurate diagnostic tools more effective in detecting paucibacillary TB in young children. Such methods should be coupled with the development of suitable platforms for detection such as incorporation of validated markers into rapid point-of-care tests that are feasible to use in resource-limited settings. Such tests would ideally use readily obtainable paediatric specimens including small volumes of whole blood, serum/plasma, saliva, stool or urine. The utility of such markers was investigated in children screened for TB in a setting with high TB incidence

Methods

Results

Discussion

Conclusion