Relationship of Parasitic Index and Cytokine Profile in Canine Visceral Leishmaniasis

Abstract

Visceral leishmaniasis (VL) is a zoonotic parasitic disease caused by Leishmania infantum (L. chagasi) that infects cells of the monocyte-phagocyte system. This work aims to describe the bone marrow parasitism in dogs naturally infected by L. chagasi, and to correlate with serum concentrations of cytokines and antibody level. It evaluated 42 dogs, 21 uninfected and 21 infected by L. infantum, of both sexes and of different ages; dogs were classified into three clinical stages: stage I, mild disease; stage II, moderate disease; and stage III, severe disease. Parasitic index was determined by real-time polymerase chain reaction (PCR) and cytokine serum concentration by flow cytometry. The average parasitic index of infected dogs was 4.59 × 1010 copies/μl. IL-4 and TNF-α concentrations were higher in infected dogs than in the control group. Antibody levels were positively correlated with IL-4 expression. There was a significant positive correlation of IL-6 cytokine levels with the evolution of stages I and III. Antibody levels were positively correlated with IL-4 expression. There was a significant positive correlation of IL-6 cytokine levels with the evolution of stages I and III. However, this cytokine can be used as a marker to distinguish between different clinical stages.