Can blood or urine IP-10 discriminate between active and no active tuberculosis in children?

Abstract

Background: Childhood tuberculosis (TB) is an urgent problem as TB diagnosis in children is difficult to perform. Interferon-γ-inducible protein-10 (IP-10), either in blood or urine, has been proposed as TB biomarker for adults. Aims and objectives: To evaluate the IP-10 diagnostic potentials in children from Uganda, a high TB-endemic country. Methods: IP-10 was measured in blood and urine concomitantly taken from children prospectively enrolled with a suspect of active TB with or without HIV-infection. Clinical/microbiological parameters and TB-immune assays commercially available [tuberculin skin test (TST) and QuantiFERON (QFT)] were evaluated. Results: Data on 111 children, on whom a concomitant evaluation of blood and urine IP-10 was available, were analyzed. Eighty children were HIV-uninfected and 31 HIV-infected. 33 healthy donors adults (HDA) were included as controls. IP-10 is detectable in blood and urine of children with active TB independently from age and associate with M.tuberculosis load. Blood IP-10 was significantly higher in active TB children compared to HDA in both HIV-infected (p≤0.0001) and -uninfected subjects (p≤0.0001); urine IP-10 was significantly increased in HIV-infected active TB children versus HDA (p=0.05). However, the accuracy of both IP-10 tests to distinguish active TB from “no active TB” was low and similar to TST and QFT. Conclusion: These results, although insufficient for TB diagnosis, suggest that blood and urine IP-10 allow to assess the state of immune activation and can be used as a potential inflammatory marker for clinical work-up, evaluated easier than the established blood tests such as C-Reactive Protein or Erytrocytes Sedimentation Rate.