Molecular mechanisms and biology significance of polysaccharide recognition by the immune system / 中国免疫学杂志

ABSTRACT

As monosaccharide polymers,polysaccharides are widely distributed in nature,they are found in microorganisms,plants and animal cells and tissues.Glycosylation is of importance to maintain the structural stability and biological activity of protein molecules in eukaryotic cells.Polysaccharides represent the most important antigens recognized by immune system.The innate immune system senses invading microbes via their pathogen-associated molecular patterns,using pattern-recognition receptors on the surface of innate immune cells,many of which are polysaccharides uniquely expressed in certain microorganisms.Polysaccharides can also be processed intracellularly and presented to ??-T cells by MHC molecules.Polysaccharides can activate B lymphocytes,with or without T cell help,and induce production of specific antibodies.Amongst the polysaccharide-specific antibodies in human sera,some are products of adaptive humoral responses against microbial infection and others autoantibodies to glycan epitopes of host cells.Patients with autoimmune disorders tend to have higher titers of antibodies against various glycans.Immune clearance of senescence cells depends on the recognition of altered glycan epitopes on cell surface.Modification of glycan epitopes on tumour cell surface is at least partially responsible for activating antitumor immunity.Specific recognition of polysaccharides by the immune system is of importance to immunological defence,autoimmunity,anti-tumour immunity and immunological homeostasis,it will be the new focus of immunology research in the near future.