Complex Glycans and Immune Regulation

The immune system continually uses protein-carbohydrate interactions in homeostasis and disease. Glycoconjugates (i.e., glycoproteins, proteoglycans, glycolipids) decorate mammalian or microbial cell surfaces, as well as viral particles. These glycan structures can be recognized by glycan-binding proteins, which typically induce signaling response whereby the immune response can be categorized as pro- or anti-inflammatory. These processes can also be influenced at numerous stages of immune cycling, including self vs. non-self-discrimination, immune cell survival, or cell trafficking to areas of infection and/or inflammation. In this article, we review immunoregulatory properties of host- and microbe-associated glycoconjugates in health and disease. Immune regulation, in broad terms, is complex mechanisms of physiological control of immune cell function to balance between activation and suppression. These mechanisms can occur through direct cell-cell interaction, cytokine signaling, or gene regulation to prevent overstimulation of immune responses.