Avaliação da hiperplasia tímica e alterações imunopatológicas da medula óssea durante a infecção aguda por Leishmania amazonensis em modelo murino

Abstract

Leishmaniasis is a heterogeneous group of diseases caused by protozoa of the genus Leishmania sp. The control of infection by leishmania and dependent cell-mediated immune response, the macrophage and the main cell effector in eliminating the amastigote after its activation by helper T lymphocytes (helper). Lymphocytes are produced in primary lymphoid organs, including bone marrow and thymus, bone marrow is the production of all precursor lymphocytes and mature B cells and in the thymus T cells mature and migrate to secondary lymphoid organs. In a recent publication, using a murine model of infection with L. amazonensis demonstrated thymic involvement with organ hyperplasia and derangement of architecture. Continuing the study, we analyzed the immunopathological changes induced in the bone marrow and correlated with thymic hyperplasia observed. Therefore, we used inbred mice of the BALB / c strain, females aged between 6 and 8 weeks, the parasite amastigotes were inoculated in the footpad of the hind leg, being used 28 animals divided into seven groups, control, 24 hours, 3, 5, 7, 15 and 30 days after infection. The animals were killed and the femurs and thymus removed, the collection of peripheral blood was carried out, bone marrow aspirate, thymus weight, Histological analysis of thymus and bone marrow, myelogram, relation myeloid:erythroid and leukogram. Confirmed thymic hyperplasia with increased cellularity and loss of demarcation between cortex and medulla. We observed an increase in cellularity of bone marrow, hypoplasia of the myeloid lineage mainly myelocytes and

megakaryocytic lineage, hyperplasia of erythroid lineage characterized by increased pro- rubrócitos and lymphoid observed on the 15th day of infection. The relation myeloid:

erythroid observed reduction cells of the myeloid lineage and increase the erythroid lineage cells. The leucocyte count showed increased eosinophils, neutrophils and monocytes and reduction of lymphocytes. These changes were immediately observed after 24 hours of infection and peak occurred at 3 to 5 day. We conclude that changes in the bone marrow may have contributed to the hyperplasia of the thymus and that the two organs are greatly affected in the acute infection by Leishmania amazonensis.