Visceral leishmaniasis (VL) is a potentially fatal disease, in which the treatment based on
chemotherapy is considered toxic. The cure of disease is associated with the life-long Th1-type immunity against the
infection. The Th1-related
cytokines production by peripheral blood mononuclear cells (PBMCs) seems to be crucial for host control of parasite load and clinical cure. In the current study, we used five
proteins (
IgE-dependent
histamine-releasing factor [HRF], LiHyD, LiHyV, LiHyT and LiHyp6) recently shown to be antigenic and/or immunogenic in the canine VL, aiming to evaluate the
antigen-specific antibody levels and
cytokine production in PBMCs culture supernatants collected from VL patients before and after anti-VL treatment. In the results, when PBMCs were exposed to rHRF, rLiHyD and rLiHyT, higher IFN-γ and lower
IL-10 levels were observed in all patients that were treated and clinically cured. Analysis of specific antibody subclasses was in line with in vitro cellular response, since a higher
IgG2 production was found in the treated and cured patients, when compared to the
IgG1 subclass levels. In addition, evaluating the diagnostic efficacy of the recombinant molecules, the rHRF, rLiHyD and rLiHyT
proteins showed the best results in the serology assays to identify all VL patients, as well as these
antigens were not recognized by
antibodies in sera from non-infected subjects or those with
leishmaniasis-related diseases. Our results corroborate the view that clinical cure of VL is associated with a sustained Th1-related response, and indicate the potential use of rHRF, rLiHyD and rLiHyT as immune
biomarkers of VL treatment.