Response of CD4+ and CD8+ T lymphocytes in the evolution of Leishmania (Viannia) shawi infection

Leishmania (Viannia) shawi was recently characterized, and there are no studies of immunopathological alterations induced by this parasite. BALB/c and C57BL/6 mice were infected in the footpad with L. (V.) shawi promastigotes. The lesions were monitored during 8?weeks post-infection (pi), and at each 2?weeks pi, immunohistochemistry of skin and lymph nodes has been performed to analyze the densities of CD4+ and CD8+ T lymphocytes as well as amastigote forms. In the skin, BALB/c mice presented higher amastigote densities than C57BL/6 mice; concerning lymphocytes, there are no significant differences between CD4+ T lymphocytes densities; however, C57BL/6 mice presented elevation in densities of CD8+ T cells latter in the infection. The elevation of amastigote densities in lymph nodes of BALB/c mice at 8?weeks pi could be a reflection of suppressed density of CD4+ T. On the other hand, elevated density of CD8+ T lymphocytes in lymph nodes of C57BL/6 seems to exert some degree of resistance compared to BALB/c mice. The present work indicates that CD8+ T lymphocyte can be a key component to generation of resistance in L. (V.) shawi infections.