Specific interaction of IgE antibodies with a carbohydrate epitope of honey bee venom phospholipase A₂

Abstract

Phospholipase A2 (E.C. 3.1.1.4.) is a major allergen of honey bee venom. It exists in a glycosylated and an unglycosylated variant. Both forms and the glycopeptide isolated after exhaustive proteolytic digestion were tested in RAST and RAST inhibition studies. IgE from 11 of 14 bee venom allergy sera exhibited significantly higher, and in two cases exclusive, affinity towards glycosylated phospholipase. In RAST inhibition experiments using phospholipase coupled to discs five of the sera were completely inhibited by glycopeptide at 0.1 mg/ml; four sera were partially inhibited and two sera could not be inhibited. Glycoasparagine, lacking all amino acids except the carbohydrate-linking asparagine, inhibits IgE-binding to glycopeptide discs up to 100%. These data clearly demonstrate that an oligosaccharide of a structural type frequently found in glycoproteins can represent an epitope which is recognized by IgE antibodies from allergic patients, which are specifically directed against the parent glycoprotein.

Haemonchus contortus Glycoproteins Contain N-Linked Oligosaccharides with Novel Highly Fucosylated Core Structures

“…The Fuc␣(1-3)GlcNAc moiety has been shown to be a highly antigenic epitope of both plant (28) and insect (29) glycoproteins and also accounts for the immunogenic cross-reactivity between plant and insect glycoproteins (29). This structure has also been shown to be a major allergenic determinant in phospholipase A 2 , and individuals who are allergic to honeybee venom produce appreciable levels of IgE antibodies to the 3-linked fucose of the N-glycans of this glycoprotein (19,30). In addition, Fuc␣(1-3)GlcNAc is an important component of the Le x , Le y , Sialy-Le x , and VIM-2 blood group determinants, which have been implicated in selectin-mediated trafficking of lymphocytes, inflammatory processes, apoptosis, and other cell-cell interactions in mammals (14,31,32).…”

The N‐linked oligosaccharides of aminopeptidase N from Manduca sexta

“…This substitution is also the major allergenic determinant in honeybee PLA 2 [4,5,7]. Individuals who are allergic to honeybee venom produce appreciable levels of antibodies to the 3-linked fucose of the N-glycans in this protein [7,8]. The high abundance of the novel highly fucosylated N-glycans at three N-glycosylation sites on the APN protein indicates that they are a prominent feature on the midgut membrane surface and could plausibly play a role in mediating protein-protein interactions.…”

“…However, the Fuca(1-3)GlcNAc moiety has been shown to be a highly antigenic epitope of both plant [35] and insect [36] glycoproteins and also accounts for the immunogenic cross-reactivity between plant and insect glycoproteins [36]. This substitution is also the major allergenic determinant in honeybee PLA 2 [4,5,7]. Individuals who are allergic to honeybee venom produce appreciable levels of antibodies to the 3-linked fucose of the N-glycans in this protein [7,8].…”

“…In the context of this application, it is crucial to realize the differences between insect and mammalian N-glycan processing pathways because N-glycans are known to influence many different protein properties and functions, which include enzymatic activity, conformation and immunogenicity. For example, the Fuca(1-3)GlcNAc substitution, found in a small proportion of N-glycans on honeybee PLA 2 is the major allergenic determinant in this protein [4,5,7], and individuals who are allergic to honeybee venom produce high levels of antibodies to the 3-linked fucose moiety [7,8].…”

Comparison of soluble and secreted forms of human parainfluenza virus type 3 glycoproteins expressed from mammalian and insect cells as subunit vaccines

“…The oligosaccharide structures added to glycoproteins by insect cells differ from those found on proteins made in mammalian cells (Hsieh & Robbins, 1984;Weber et al, 1986;Kuroda et al, 1990;Wathen et al, 1991 ;Aeed et al, 1992) and carbohydrate structure has been shown to contribute to protein antigenicity (Weber et al, 1987;Moore et al, 1990). In one such study Moore et al (1990) showed that a significant proportion of the antigpl20 antibodies found in human immunodeficiency virus-positive human sera recognize epitopes that are dependent on the glycosylation pattern.…”