Immunodetection of CD4 and CD8 T Cell in Dogs with Visceral Leishmaniasis - Abstract
The aim of this study was to analyze different organs of dogs with VL for the presence of parasite and the proportion of two lymphocyte subtypes (CD4/CD8). Symptomatic (S=17) and asymptomatic (A=12) dogs from endemic area for VL were used. Control group (C=6) had dogs from non-endemic area. The detection of parasite DNA (RT-qPCR) and T cells (immunohistochemistry) was done on skin, lymph nodes, spleen and liver. The results were compared by group. The spleen of symptomatic dogs showed the highest levels of parasite DNA, followed by lymph nodes, skin and liver. CD4/CD8 T cells predominated in asymptomatic dogs and differed significantly from symptomatic and control groups (P<0.05). The CD4 T cells immunodetection was higher than CD8 in all organs of infected dogs. The skin had low parasite load
and high immunodetection of T-cells subpopulations in the asymptomatic group. The same group showed positive correlation between CD4 T cells and parasite load in skin. The symptomatic group had negative correlation between CD4 and parasite load on lymph nodes, and CD8 and parasite load in spleen and lymph nodes. In the symptomatic group, the lymphoid organs had the highest parasite load and it
suggesting most susceptibility to infection by the Leishmania spp. This organ had low number of CD8 T-cells in the symptomatic group, suggesting an inefficient cellular response. Possibly, part of the sub-population of CD4 could be regulatory T-cells and this will be contributing to the maintenance of the infection in susceptible organs, such as the spleen.