The Study Of The Mucosal Immune System Of Monopoterua Albus

Fish belongs to the vertebrate, and the systematic immunity is incomplete, but the mucousal immunity which take the mucous immune system as the foundation is developed. The mucosa-associated lymphyoid tissues in teleost fishes include the gut,skin and gills. These tissues with their layer of mucus and array of nonspecific immune defences are exposed to the external environment and form the initial barrier to invasion by pathogens. The mucosal immune system plays an important role in fish immunity and already given more attention on it.This paper investigated the morphology and histology of the mucosa-associated lymphyoid tissues of the rice eel including digestive tract, skin and so on. In addition we also tested the location and characteristics of the Ig and Ig-positive cells in the mucosa-associated lymphyoid tissues in order to futher studies fish mucous immunity mechanism.Using microscopy and histochemistry technology, microstructure of the morphologic and immune-associated cells involved in digestive tract and skin were studied.The results showed that few lymphocytes in pharynx, esophagus and stomach, lymphocytes distributed widely in the intestine and skin, the number of lymphocytes in back epidermis was bigger than that in the abdomen epidermis and the number of IELs(Intraepithelial lymphocytes) in intestine was bigger than LPLs(Lamina propria lymphocytes). There was no significant difference among the quantity of lymphocytes in foregut, midgut and posterior intestine. Because of the frequent parasite infection in foregut, there were massive EGCs(Eosinophil granular cells) appeared, the number was bigger than that in midgut and posterior intestine.The AB-PAS dyeing result indicated that mucus cells were distributed widely in the intestine and skin, they were divided into three kind of types: blue color, AB positive, PAS negative, including acidic mucopolysaccharide; purple red color, AB and PAS positive, simultaneously includes the neutral mucopolysaccharide and the acidic mucopolysaccharide but the neutral mucopolysaccharide primarily; royal purple color, simultaneously includes the neutral mucopolysaccharide and the acidic mucopolysaccharide but the acidic mucopolysaccharide primarily. The majority of the mucus cells in the skin belonged to the first kind of type. These three kinds of cells all existed in the pharynx and esophagus, the majority of the mucus cells in the pharynx belonged to the third kind of type, and in the esophagus which mucus cells belonged to the first kind of type.Both had a few mucus cells of the second kind type. The majority of the mucus cells in the gut were the third kind of type.Serum immunoglobulin (Ig) from rice eel(Monopterus albus) was purified by Hitrap protein A HP affinity purification and assessed by sodium dodecyl sulphate polycarylamide gel electrophoresis (SDS-PAGE). The results indicated that the serum IgM can be separated into three subunits: the heavy chain and the two light chains, the molecular masses were 72kDa, 28kDa and25.3kDa, respectively. According to the results of electrophoretogram analysis, Ig also existed in the mucus of intestine and skin. Sera anti-IgM of Monopterus albus had been prepared by repeatedly immunized New Zealand rabbits, and the titers of anti-sera obtained up to 1:32 by double diffusion. Western-blotting indicated that the heavy chain of sera, cutaneous and intestine Ig can specificity binding Sera anti-IgM of Monopterus albus.The results of immunohistochemistry showed Ig-positive cells occasionally were found within the epithelial layer of the skin and the mucosa of stomach. An obvious feature of the mucosal tissues was the number of Ig-positive within the lamina epithelialis in intestine were more than within the lamina propria.And the Ig+ cells were rich through the whole gut.In this study, we drew a conclusion that a large number lymphocyte and immune-associated cells existed in the mucosa-associated lymphyoid tissues, which indicated that the mucosal immune system of rice eel could complete the immunological response independent of systematic immune system.