Evaluation of spleen cell population and effect of splenectomy on granuloma modulation in BALB/c mice infected with Schistosoma mansoni

Abstract

A kinetic study of the cells present in the spleen of BALB/c mice infected with Schistosoma mansoni was carried out. The lymphocytes were evaluated phenotypically with monoclonal antibodies and the effect of splenectomy on the modulation of periovular granuloma was also investigated. The infected mice had proportional increases in the numbers of neutrophils, plasma cells, macrophages and eosinophils in the spleen. The largest number of neutrophil, plasma cells and macrophage were found between the 8th and the 12th week of infection, while the amount of eosinophils were higher later on, around the 20th week. The lymphocytes phenotypically characterized as Thy 1.2, Lyt 1.2 (CD4) increased mildly in proportional numbers. However, the percentage of lymphocytes with the Lyt 2.2 (CD8) phenotype, which is characteristic of suppressor and cytotoxic T cells, increased significantly with the progress of the disease. The numbers of B lymphocytes, which comprise 50% of the mononuclear cells present in the spleen, increased significantly till the 16th week when they began to decrease. The mean diameters of periovular granulomas were comparatively similar in both experimental groups (splenectomized and non-splenectomized mice). However, the evolutive types of granuloma (exudative, intermediate and fibrous) in splenectomized mice were proportionally different from those of non splenectomized mice in the 16th and 24th week of infection. It is inferred that lymphnodes or other secondary lymphoid organs, in the absence of the spleen, assume a modulating action on periovular granulomas, although the evolution of the granulomas is somehow delayed in splenectomized mice.

Role of the spleen on the pathogenesis of schistosomal periportal (pipestem) fibrosis of the liver: an experimental approach.

“…21 Experimentally, splenectomy failed to modify the size and type of periovular granulomas in the liver, except when performed on the eighth week of infection, when the reaction around the eggs was enhanced in splenectomized mice. 22,23 Under the present experimental conditions, the presence of the spleen seemed important, but not essential, for the development of periportal hepatic fibrosis (pipestem fibrosis) in mice chronically infected with S. mansoni. A statistically significant proportion of the cases occurred in nonsplenectomized animals compared with those that were splenectomized.…”

O peso do baço em chagásicos crônicos

“…Foi encontrado ainda, um retardo na evolução dos granulomas periovulares em ratos esplenectomizados, quando linfonodos ou outros órgãos linfóides secundários assumem o papel modulador 5 .…”