Protein and lipid glycosylation can be said to be at the very heart of immunology. The first line defense of the innate immune system is based on recognition of carbohydrates. The acute phase response and classical, immunoglobulin regulated, immunity are mediated by glycoproteins and some of the early antigens to be characterized were the carbohydrate blood groups. Blood group related structures are the first signals in attracting leucocytes to the sites of infection (via selectins) and the infectious microorganisms themselves are highly glycosylated. Recently glycopeptides and GPI membrane anchors of glycoproteins have been implicated in the T cell arm in so-called, non-classical MHC immune reactions. Some of the best candidates for cancer immunotherapy are sugar-based, but on the other hand antibodies to an oligosaccharide antigen are a major obstacle in xenotransplantation.
This Chapter tracks the fate of the invading organism, concentrating on bacteria and the immune reaction against them. It reviews new information on the resulting pathology (microbial pathogenesis, inflammation and autoimmunity) and addresses how the immune system is controled to lead to opsonization and apoptosis rather than toxic shock. It raises the question of how we can pervert this control to increase immune reactions against cancer cells, but reduce them in xenotransplantation. For both B and T cell responses there is a distinct role of interacting molecules which are highly glycosylated (mucin and mucin-type molecules). Immunoglobulins are glycosylated too and for the reasons to be discussed one needs to be aware of this in their use in immunotherapy.
63.1 Infection and Pathogenesis
Although there are many infectious organisms: viruses, mycobacteria, trypanosomes and other parasites, yeasts, prions etc, bacteria hold a major historical centerstage position. Pathogenic bacteria are categorized into two groups, Gram-negative