Donor antibodies, administered intravenously or subcutaneously, make up a commercial product used to treat both immunodeficiencies and inflammatory or auto-immune diseases.
These preparations contain a complex mix of antibodies against glycans, the carbohydrate molecules on the outsides of cells, a Jan. 7Â paper in Science Translational Medicine reveals.
At first glance, the findings are remarkable because:
A. Immunologists have long thought that carbohydrates, by themselves, are not good at provoking the immune system. (The assumption was: you need some protein for antigen presentation and getting T cells interested.) The data shows exceptions to the rule.
B. Some of the antibodies react against human carbohydrate structures. Instead of attacking them in an auto-immune fashion, they may actually be blocking viruses or bacteria from using those structures as gateways to infection.
The lab of Stephan von Gunten at the University of Bern collaborated with the National CenterÂ for Functional Glycomics led by biochemists Rick Cummings and David Smith at Emory to analyze the spectrum of carbohydrate structures bound by donor antibodies. This is one of those systems biology approaches generating huge amounts of data for other investigators to pore over. The Emory team has done this type of analysis on a small scale with human milk previously.
Some antibodies were identified that were specific for microbial carbohydrate-based antigens, and others for a broad spectrum of human glycans that are used as attachment sites for viruses and bacteria or their toxins. This anti-glycan repertoire may be fundamental to aid humans in preventing or limiting microbial infections. The repertoire of such antibodies in any individual could be useful in predicting disease susceptibility or resistance. This new systems biology approach to analyze immune responses to identify glycan antigens may be important in the future to vaccine design, diagnostic assays, and antibody-based therapies.