Immunoactivation depends upon the antigen potential to modulate T-cell repertoires. The present study has enumerated the effect of 61 kDa recombinant Leishmania donovani co-factor-independent phosphoglycerate mutase (rLd-iPGAM) on mononuclear cells of healthy and treated visceral leishmaniasis subjects as well as on THP-1 cell line. rLd-iPGAM stimulation induced higher expression of interleukin-1β (IL-1β) in the phagocytic cell, its receptor and CD69 on T-cell subsets. These cellular activations resulted in upregulation of host-protective cytokines IL-2, IL-12, IL-17, tumour necrosis factor-α and interferon-γ, and downregulation of IL-4, IL-10 and tumour growth factor-β. This immune polarization was also evidenced by upregulation of nuclear factor-κ light-chain enhancer of activated B cells p50 and regulated expression of suppressor of mother against decapentaplegic protein-4. rLd-iPGAM stimulation also promoted lymphocyte proliferation and boosted the leishmaniacidal activity of macrophages by upregulating reactive oxygen species. It also induced 1·8-fold higher release of nitric oxide (NO) by promoting the transcription of inducible nitric oxide synthase gene. Besides, in silico analysis suggested the presence of major histocompatibility complex class I and II restricted epitopes, which can proficiently trigger CD8+ and CD4+ cells, respectively. This study reports rLd-iPGAM as an effective immunoprophylactic agent, which can be used in future vaccine design.
Keywords: Leishmania donovani; adaptive immunity; co-factor-independent phosphoglycerate mutase; innate immunity; visceral leishmaniasis.