Immunological changes in canine peripheral blood leukocytes triggered by immunization with first or second generation vaccines against canine visceral leishmaniasis

In this study, we summarized the major phenotypic/functional aspects of circulating leukocytes following canine immunization with Leishvaccine and Leishmune ®. Our findings showed that Leishvaccine triggered early changes in the innate immunity (neutrophils and eosinophils) with late alterations on monocytes. Conversely, Leishmune ® induced early phenotypic changes in both, neutrophils and monocytes. Moreover, Leishvaccine triggered mixed activation-related phenotypic changes on T-cells (CD4 + and CD8 +) and B-lymphocytes, whereas Leishmune ® promoted a selective response, mainly associated with CD8 + T-cell activation. Mixed cytokine profile (IFN-γ/IL-4) was observed in Leishvaccine immunized dogs whereas a selective pro-inflammatory pattern (IFN-γ/NO) was induced by Leishmune ® vaccination. The distinct immunological profile triggered by Leishvaccine and Leishmune ® may be a direct consequence of the distinct biochemical composition of these immunobiological, i.e. complex versus purified Leishmania antigen along with Bacillus Calmette-Guérin (BCG) versus saponin adjuvant. Both immunobiologicals are able to activate phagocytes and CD8 + T-cells and therefore could be considered as a putative vaccines against canine visceral leishmaniasis (CVL).