Efficacy against VL was mediated by a CD4<sup>+</sup>TNF-α T lymphocyte response against the NH36-F3 domain, while against tegumentary leishmaniasis (TL) a CD8<sup>+</sup> T lymphocyte response to F1 was also required.
The protection against VL was associated with increased production of nitric oxide (NO), interferon gamma (IFN-γ), IL-17A, and tumor necrosis factor alpha by splenic cells restimulated <i>ex vivo</i> with <i>L. infantum</i> antigens.
However, lymphocytes from sVL stimulated with SLA had lower percentages of CD4<sup>+</sup> and CD8<sup>+</sup> cells expressing CD69 and CD8<sup>+</sup> cells expressing CD25, with no release of interferon-γ or tumor necrosis factor. sVL subjects had lower percentage of memory cells (CD4<sup>+</sup> CD45RO+), ex vivo, without SLA stimulation than RecVL, LST+, or LST- (<i>P</i> = 0.0022).
Leptin-induced IFN-γ, IL-2, and TNF-α cytokines in the culture supernatant of splenocytes upon soluble leishmanial antigen (SLA) stimulation and significantly up-regulates serum IgG2a titers, which help to generate Th1 immune response in VL.
Visceral leishmaniasis (VL) is associated with increased circulating levels of multiple pro-inflammatory cytokines and chemokines, including IL-12, IFNγ, and TNFα, and elevated expression of IFNγ mRNA in lesional tissue such as the spleen and bone marrow.
Immunization with rLdp45 exerted considerable prophylactic efficacy (∼85%) supported by an increase in mRNA expression of iNOS, IFN-γ, TNF-α and IL-12 and decrease in TGF-β and IL-4, indicating its potential as a vaccine candidate against VL.