IgE-reactive carbohydrate epitopes--classification, cross-reactivity, and clinical impact.
A glycan-related IgE-reactivity has been demonstrated in most allergen sources, especially in plant kingdom. Recent progress in glycobiology has allowed a clearer classification of these glyco-epitopes. Unlike classical peptide chain-based epitopes, glyco-epitopes can share significant structural homologies beyond the limits of protein families. These glycoepitopes are thus prone to extensive cross-reactivity. They have been called Cross-reactive Carbohydrate Determinants or CCD. Many of these glyco-epitopes behave as "panepitopes", leading to cross-reactivity between products as distant as pollens and hymenoptera venoms. But CCD are not universally cross-reactive and they rather cluster into subgroups such as plant CCD or fungal CCD. Because a monovalent IgE-binding is sufficient in serum-based assays, glyco-epitopes and CCD are classically considered as a potential source of positive in vitro results without clinical significance. But some authors recently demonstrated that glyco-epitopes could induce a response at the cell level and suggested that they might play a role in vivo. As long as in vitro assays include glycan- and CCD-related IgE responses, laboratory results should be carefully interpreted in the light of existing knowledge about the glycomes of natural products. IgE-reactivity of the patient's serum can also be tested towards a glycoprotein model such as bromelain.
Malandain
H
H
Laboratoire de Biochimie, Centre Hospitalier Chubert, 56017 Vannes, France. henri.malandain@ch-bretagne-atlantique.fr
D000818:Animals; D000918:Antibody Specificity; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000737:chemistry / Q000276:immunology*; D003429:Cross Reactions; D000939:Epitopes / Q000737:chemistry / Q000145:classification / Q000276:immunology*; D005512:Food Hypersensitivity / Q000276:immunology; D005658:Fungi / Q000276:immunology; D006023:Glycoproteins / Q000737:chemistry / Q000276:immunology; D006031:Glycosylation; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007073:Immunoglobulin E / Q000276:immunology*; D007448:Invertebrates / Q000276:immunology; D020315:Latex Hypersensitivity / Q000276:immunology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010944:Plants / Q000276:immunology; D011058:Pollen / Q000276:immunology; D011134:Polysaccharides / Q000737:chemistry / Q000276:immunology; D014714:Vertebrates / Q000276:immunology
D002241:Carbohydrates; D000939:Epitopes; D006023:Glycoproteins; D011134:Polysaccharides; D007073:Immunoglobulin E