Avaliação da carga parasitária, produção de citocinas e alterações histológicas em camundongos Balb/c submetidos à esplenectomia e ao implante autógeno de baço após infecção com Leishmania chagasi

Abstract

The autogenous implant of spleen is an option for the preservation of splenic function after total splenectomy. Although it has been demonstrated that splenectomized individuals are more sensitive to infections by various bacteria, few reports existing on the importance of the spleen in resistance to infection by Leishmania sp. Leishmaniasis is an infectious disease caused by an unicellular flagellate protozoa, which survive in macrophages after phagocytosis. The objective of this work was to evaluate the influence of splenectomy and autogenous implant of spleen on the parasitic load and in the production of IFN-, IL-12, TNF-,IL-10 and IL-17 in the liver and spleen of BALB/c mice infected intraperitoneally (i.p.) with 106 promastigotes of L. chagasi. Presence of inflammatory infiltrate in the liver of the infected animals was also evaluated, through hematoxylin-eosin staining of tissue cuts embedded in paraffin. BALB/c mice were divided into the following groups: splenectomized (SP), splenectomized and autotransplanted in the greater omentum (AT), and control group with sham operation (CT). Thirty days after the surgery the animals were infected i.p. with 106 promastigotas of L. chagasi. After thirty days of infection the animals were euthanized, the spleen and the liver collected, macerated, and used for evaluation of the parasitic load through the technique of limiting dilution, and for production of cytokines through the method of ELISA. The results obtained show that the splenectomized animals presented a larger parasitic load when compared to the CT and AT groups, having also a greater production of IL-10 in the liver. On the other hand, the CT and AT groups showed greater production of IFN-, IL-12 and TNF- than the splenectomized group. The production of IL-17 was greater in the liver of the splenectomized animals. In the splenectomized animals few infiltrates of mononuclear cells were observed, in comparison to the animals with intact spleen, which showed a moderate accumulation of mononuclear cells in the liver. The results obtained suggest that the presence of the spleen favors the development of a more effective immune response to infection with L. chagasi, this being correlated with an elevated production of pro-inflammatory cytokines with Th1 profile, and greater recruitment of mononuclear cells to the infection site. However, splenectomy can interfere in the pattern of immunologic reponse of animals infected with Leishmania chagasi, leading to a greater sensitivity to the infection.