Immunological profile of resistance and susceptibility innaturally infected dogs by Leishmania infantum.

Abstract

Visceral leishmaniasis has a great impact on public health, and dogs are considered the maindomestic reservoir of Leishmania infantum, the causal parasite. In this study, 159 animalsnaturally infected by L. infantum from an endemic area of Brazil were evaluated through ananalysis of cellular responses, using flow cytometry, and of the hematological parameters.The results confirmed that disease progression is associated with anemia and reductionsin eosinophils, monocytes and lymphocytes. The investigation of the immune response,based on the immunophenotypic profile of peripheral blood, showed declines in the abso-lute numbers of T lymphocytes CD5+and their subsets (CD4+and CD8+) and a drop of Blymphocytes in asymptomatic seropositive (AD-II) and symptomatic seropositive (SD) dogs.Neutrophils, when stimulated with soluble antigen of L. infantum, showed higher synthesisof interferon (IFN)- _+in AD-II and SD groups, with decreased production of interleukin