Potential Role for Mycobacterium tuberculosis Specific IL-2 and IFN-γ Responses in Discriminating between Latent Infection and Active Disease after Long-Term Stimulation

PLoS One. 2016 Dec 29;11(12):e0166501. doi: 10.1371/journal.pone.0166501. eCollection 2016.

Abstract

Interferon gamma release assays (IGRAs) could accurately diagnose Mycobacterium tuberculosis (M.tuberculosis) infection. However, these assays do not discriminate between latent tuberculosis infection (LTBI) and active tuberculosis disease (ATB). Here, a total of 177 subjects, including 65 patients with ATB, 43 subjects with LTBI, and 69 TB-uninfected controls (CON group) were enrolled. The concentration of IFN-γ, IP-10, and IL-2 was determined in peripheral blood mononuclear cells (PBMCs) after short-term (24h) or long-term (72h) stimulation with TB antigens including ESAT-6/CFP-10 (EC) and purified protein derivative (PPD).EC-stimulated IL-2 and gamma interferon-inducible protein 10 (IP-10) release (24h and 72h) showed a good diagnostic performance in distinguishing between TB-infected and TB-uninfected individuals, but failed to discriminate between ATB and LTBI. After 72h of incubation, the release of IL-2 was higher in LTBI patients after stimulation with EC and PPD. The PPD-stimulated IL-2/IFN-γ ratio after 72h incubation had the diagnostic potential to discriminate between ATB and LTBI, with a sensitivity of 90.8% and a specificity of 97.7%. In addition, these new biomarkers, combined with T-SPOT test in a two-step strategy, were validated with high levels of accuracy in a prospective clinical-based cohort. Collectively, the PPD-stimulated IL-2/IFN-γ ratio after long-term incubation may be an alternative diagnostic biomarker in distinguishing between active TB patients and subjects with latent infection.

MeSH terms

  • Adult
  • Aged
  • Antigens, Bacterial / immunology
  • Bacterial Proteins / immunology
  • Biomarkers / analysis
  • Communicable Diseases / diagnosis*
  • Female
  • Humans
  • Interferon-gamma / metabolism*
  • Interferon-gamma Release Tests
  • Interleukin-2 / metabolism*
  • Latent Tuberculosis / diagnosis*
  • Latent Tuberculosis / immunology
  • Leukocytes, Mononuclear / immunology
  • Leukocytes, Mononuclear / metabolism*
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis / immunology*
  • Prospective Studies
  • Tuberculin Test
  • Tuberculosis, Pulmonary / diagnosis*
  • Tuberculosis, Pulmonary / immunology
  • Tuberculosis, Pulmonary / pathology
  • Young Adult

Substances

  • Antigens, Bacterial
  • Bacterial Proteins
  • Biomarkers
  • CFP-10 protein, Mycobacterium tuberculosis
  • ESAT-6 protein, Mycobacterium tuberculosis
  • IL2 protein, human
  • Interleukin-2
  • Interferon-gamma

Grants and funding

This work is supported by the Tongji University School of Medicine Research Fund (11-046, To W.S.). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.