Reassessment of immune correlates in human visceral leishmaniasis as defined by cytokine release in whole blood

Clin Vaccine Immunol. 2012 Jun;19(6):961-6. doi: 10.1128/CVI.00143-12. Epub 2012 Apr 25.

Abstract

Depressed cell-mediated immunity in human visceral leishmaniasis (VL) (also known as kala-azar), revealed as the inability of peripheral blood mononuclear cells (PBMCs) to respond to Leishmania antigen, remains a hallmark of and is thought to underlie the progressive nature of this disease. We recently reported the ability of a whole-blood, gamma interferon (IFN-γ) release assay to detect subclinical infections among healthy individuals living in an area where kala-azar is endemic (Bihar, India) and the surprising result that patients with active VL also secreted significant levels of antigen-specific IFN-γ in this assay. We were interested in ascertaining whether these findings would be true for a larger cohort of subjects and in employing the whole-blood assay to detect additional cytokines that might better correlate with the disease status of infected individuals. We evaluated IFN-γ, tumor necrosis factor alpha (TNF-α), and interleukin-10 (IL-10) release in 35 patients with active VL, 54 patients with VL who were cured, 27 patients with other diseases, 52 healthy controls who lived in regions where VL or kala-azar is not endemic (NEHCs [for nonendemic healthy controls]), and 147 healthy controls who lived in regions where kala-azar is endemic (EHCs [for endemic healthy controls]). The cellular responses of the EHCs were correlated with their serological antibody titers against Leishmania donovani and Phlebotomus argentipes saliva. The whole-blood cells from the majority of both active (80%) and cured (85%) VL patients, as well as 24% of EHCs with presumed subclinical infections, produced significantly elevated levels of IFN-γ. The findings do not support a severe Th1 response defect in kala-azar. Importantly, only the patients with active VL also produced IL-10, which in conjunction with IFN-γ better reflects the immune responses that distinguish individuals with active disease from cured or subclinically infected, immune individuals.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • Antibodies, Protozoan / blood
  • Biomarkers / analysis*
  • Child
  • Female
  • Humans
  • India
  • Interferon-gamma / metabolism*
  • Interleukin-10 / metabolism*
  • Leishmania donovani / immunology*
  • Leishmaniasis, Visceral / immunology*
  • Leukocytes, Mononuclear / immunology*
  • Male
  • Phlebotomus / immunology
  • Tumor Necrosis Factor-alpha / metabolism*
  • Young Adult

Substances

  • Antibodies, Protozoan
  • Biomarkers
  • Tumor Necrosis Factor-alpha
  • Interleukin-10
  • Interferon-gamma