Interferon-Gamma release assay (modified quantiFERON) as a potential marker of infection for Leishmania donovani,a proof of concept study

Background: in areas endemic for visceral leishmaniasis (vl),a large number of infected individuals mount a protective cellular immune response and remain asymptomatic carriers. we propose an interferon-gamma release assay (ifn-γra) as a novel marker for latent l. donovani infection. methods and findings: we modified a commercial kit (quantiferon) evaluating five different leishmania-specific antigens; h2b,h2b-psa2,h2b-lepp12,crude soluble antigen (csa) and soluble leishmania antigen (sla) from l. donovani with the aim to detect the cell-mediated immune response in vl. we evaluated the assay on venous blood samples of active vl patients (n = 13),cured vl patients (n = 15),non-endemic healthy controls (n = 11) and healthy endemic controls (n = 19). the assay based on sla had a sensitivity of 80% (95% ci = 54.81-92.95) and specificity of 100% (95% ci = 74.12-100). conclusion: our findings suggest that a whole-blood sla-based quantiferon assay can be used to measure the cell-mediated immune response in l. donovani infection. the positive ifn-γ response to stimulation with leishmania antigen in patients with active vl was contradictory to the conventional finding of a non-proliferative antigen-specific response of peripheral blood mononuclear cells and needs further research. © 2011 gidwani et al.