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Proc Natl Acad Sci U S A. 2011 Aug 2;108(31):12669-74. doi: 10.1073/pnas.1108455108. Epub 2011 Jul 18.

Unique carbohydrate-carbohydrate interactions are required for high affinity binding between FcgammaRIII and antibodies lacking core fucose.

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  • 1Pharma Research and Early Development, Roche Glycart AG, CH-8952 Schlieren, Switzerland.

Abstract

Antibody-mediated cellular cytotoxicity (ADCC), a key immune effector mechanism, relies on the binding of antigen-antibody complexes to Fcγ receptors expressed on immune cells. Antibodies lacking core fucosylation show a large increase in affinity for FcγRIIIa leading to an improved receptor-mediated effector function. Although afucosylated IgGs exist naturally, a next generation of recombinant therapeutic, glycoenginereed antibodies is currently being developed to exploit this finding. In this study, the crystal structures of a glycosylated Fcγ receptor complexed with either afucosylated or fucosylated Fc were determined allowing a detailed, molecular understanding of the regulatory role of Fc-oligosaccharide core fucosylation in improving ADCC. The structures reveal a unique type of interface consisting of carbohydrate-carbohydrate interactions between glycans of the receptor and the afucosylated Fc. In contrast, in the complex structure with fucosylated Fc, these contacts are weakened or nonexistent, explaining the decreased affinity for the receptor. These findings allow us to understand the higher efficacy of therapeutic antibodies lacking the core fucose and also suggest a unique mechanism by which the immune system can regulate antibody-mediated effector functions.

PMID:
21768335
[PubMed - indexed for MEDLINE]
PMCID:
PMC3150898
Free PMC Article
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