Recently, the team of Zhang Yongan, a professor at the School of Fisheries of Huazhong Agricultural University, took grass carp as the research object, and analyzed the cellular and molecular mechanisms by which chitosan oligosaccharide induces the differentiation of fish B cells and produces natural IgM, thereby enhancing the humoral immunity of fish. The research is published in Carbohydrate Polymers.
The study found that chitosan oligosaccharide can bind to the mannose receptor (MR) and integrin (Integrin) on the surface of fish B cells to activate downstream signaling pathways, and finally strongly induce the proliferation and differentiation of grass carp spleen IgM+ B lymphocytes into IgMlo and IgMhi B. Cell subsets, of which IgMlo B cells were confirmed to be a class of plasmablasts that express low IgM on the membrane surface and are able to secrete native IgM.
In vivo experiments further confirmed that chitosan oligosaccharide-induced proliferation of IgMlo plasmablasts can migrate from the spleen to the blood and secrete a large amount of natural IgM that can target pathogen-associated molecular patterns (PAMPs), thereby improving the disease resistance of fish.
The study revealed for the first time the cellular and molecular mechanisms of chitosan oligosaccharide to enhance the humoral immunity of fish, and provided a strong theoretical support for the application of chitosan oligosaccharide in fish aquaculture. In addition, the study further clarified the innate immune properties of fish B cells, and provided a good model for studying the differentiation of fish B cells.