title: The role of mast cells during experimental Schistosomiasis mansoni in mice
Creators: name: Kermanizadeh, Parviz
Publisher: name: University of Glasgow
Year: 1997
Subjects: subject: Immunology, parasitology, mast cells, Schistosoma mansoni.

description: Mast cells are important immune cells which reside in crucial sites in all organs of the body. The large number of potentially active substances which are released from the mast cell upon cell degranulation play a central role in the pathology of parasitic infections, allergic and other chronic inflammatory disorders. The influence of mast cell-derived mediators may well be important factors in atherosclerosis, anaesthesia, arthritis, angiogenesis, lipid metabolism, fibroblast interactions and other events. The association between mast cells, eosinophils and IgE antibody (three hallmarks of helminth infections and some other diseases) is of great interest. An increase in our knowledge of the processes in this association would be beneficial for the treatment and prevention of those diseases. Development of reliable methods for better investigation of mast cells and eosinophils both separately and together in tissues and body fluids was the first target of the study and a prolonged investigation resulted in the development of improved methods for fixation and staining of mast cells and eosinophils simultaneously in internal organ and skin tissues. The investigation also resulted in improving the fixation and staining of those cells separately in internal tissue. The common method of counting the cells in intestinal tissues suffers from various limitations. A new simple counting method, which could be applied to counting of the cells in the intestine and any other diffuse tissue, was developed during this investigation. The kinetics of mast cell populations in the anterior, middle and posterior portions of the small intestine and the kinetics of the mast cells and eosinophils in the liver granuloma and the association and the effect of mast cells and eosinophils on egg destruction and granuloma production were studied during a 16 week experimental Schistosoma mansoni-infection. The distribution of mast cells was always greater in the anterior than posterior portion of intestine and the number of the mast cells was greater in the intestine than in the liver (with relatively equal numbers of granulomas). On the basis of these observations and information obtained from a review literature, the possibility of mast cell attraction to nerve-derived material was proposed. The notion is that continuous stimulation of the nerve receptors or damage and degeneration of the nerve fibres by rough foreign particles (stimulants) are terminats in the release of chemoattractant material (s) from irritated nerve cells. Consequently mast cells migrate toward the injured tissue as a result of nerve-induced chemotaxis. This hypothesis not only explains the unequal distribution of mast cells in inflamed tissues but also gives a reasonable framework for consideration of possible influences on T helper cell activation. In this way mast cells which are attracted to inflamed tissues are triggered through cross-linking of high affinity IgE receptors on their surface plasma membranes. Degranulation and release of a collection of Th-1 down-regulating and Th-2 up-regulating cytokines from mast cells would lead to Th-2 type helper cell activation. For a test of this hypothesis, in vitro and in vivo experiments were designed. Pure mast cells were prepared by bone marrow culture and in vitro chemotaxis assays (culture, micro-pore and polarisation) were carried out. Promising results were achieved from polarisation assays, but because of time limitations the investigation had to be curtailed. Continuation of the in vitro and the in vivo experiments are believed to be worth considering.