The main lesion in chronic schistosomiasis represents a complex delayed-type hypersensitivity response to sequestered living, dying or dead ova, that are trapped in tissues during the peri-intestinal migration or after embolization in the liver. Soluble egg antigen (SEA) and proteolytic enzymes released by ova provoke granulomatous cell-mediated immune response, with recruitment of eosinophils, granuloma formation and liver fibrosis (Cheever et al., 2000; Wynn et al., 2004). In schistosomiasis, Th2-type cytokine production becomes predominant eight weeks post infection, while Th1 cytokines decrease as Th2 cytokines increase i.e. cross-regulation of cytokine production (Stavitsky, 2004).
Granuloma formation in the liver could be differentiated into two phases: a lytic pre-granulomatous phase (exudative phase), which produces a spherical space by destruction of parenchyma for the final establishment and organization of the lesion, and a granulomatous cellular phase (Steinberg, 1996). …show more content…
mansoni granuloma is a highly organized cellular structure, in which monocytes are the first cells that reach the site of the trapped egg, and they form the first row of cells around the egg. The cellular infiltrates around the granuloma consist of: monocytes, macrophages, lymphocytes, eosinophils, fibroblasts and plasma cells, with direct contact or adhesion between them and even between the individual cell type, through extending protrusion from the cell membrane of adjacent cells, forming an integrated network which encircles the egg. Cellular and fibrocellular granulomas are detected in the acute stage of infection, and fibrotic granulomas are seen in the chronic stage. Although, granuloma formation is mediated by T-lymphocytes, macrophages are the main cell type in cellular and fibrocellular granulomas, while macrophages and fibrocytes are the only cell type detected in fibrotic granuloma (Mansy,
Granuloma formation in the liver could be differentiated into two phases: a lytic pre-granulomatous phase (exudative phase), which produces a spherical space by destruction of parenchyma for the final establishment and organization of the lesion, and a granulomatous cellular phase (Steinberg, 1996). …show more content…
mansoni granuloma is a highly organized cellular structure, in which monocytes are the first cells that reach the site of the trapped egg, and they form the first row of cells around the egg. The cellular infiltrates around the granuloma consist of: monocytes, macrophages, lymphocytes, eosinophils, fibroblasts and plasma cells, with direct contact or adhesion between them and even between the individual cell type, through extending protrusion from the cell membrane of adjacent cells, forming an integrated network which encircles the egg. Cellular and fibrocellular granulomas are detected in the acute stage of infection, and fibrotic granulomas are seen in the chronic stage. Although, granuloma formation is mediated by T-lymphocytes, macrophages are the main cell type in cellular and fibrocellular granulomas, while macrophages and fibrocytes are the only cell type detected in fibrotic granuloma (Mansy,