Primary structures of the N-glycans of two major pollen allergens (Lol p 11 and Ole e 1) and a major peanut allergen (Ara h 1) were determined. Ole e 1 and Ara h 1 carried high mannose and complex N-glycans, whereas Lol p 11 carried only the complex. The complex structures all had a β(1,2)-xylose linked to the core mannose. Substitution of the proximalN-acetylglucosamine with an α(1,3)-fucose was observed on Lol p 11 and a minor fraction of Ole e 1 but not on Ara h 1. To elucidate the structural basis for IgE recognition of plantN-glycans, radioallergosorbent test analysis with protease digests of the three allergens and a panel of glycoproteins with knownN-glycan structures was performed. It was demonstrated that both α(1,3)-fucose and β(1,2)-xylose are involved in IgE binding. Surprisingly, xylose-specific IgE antibodies that bound to Lol p 11 and bromelain did not recognize closely related xylose-containing structures on horseradish peroxidase, phytohemeagglutinin, Ole e 1, and Ara h 1. On Lol p 11 and bromelain, the core β-mannose is substituted with just an α(1,6)-mannose. On the other xylose-containingN-glycans, an additional α(1,3)-mannose is present. These observations indicate that IgE binding to xylose is sterically hampered by the presence of an α(1,3)-antenna.

Exosomes are nanovesicles originating from multivesicular bodies that are secreted by a variety of cell types. The dual capability of exosomes to promote immunity or to induce tolerance has prompted their clinical use as vehicles for vaccination against different human diseases. In the present study, the effect of allergen-specific exosomes from tolerized mice on the development of allergen-induced allergic response was determined using a mouse model. Mice were tolerized by respiratory exposure to the olive pollen allergen Ole e 1. Exosome-like vesicles were isolated from bronchoalveolar lavage fluid of the animals by the well-established filtration and ultracentrifugation procedure, characterized by electron microscopy, Western blot, and FACS analyses, and assessed in a prophylactic protocol. To this end, BALB/c mice were intranasally treated with tolerogenic exosomes or naive exosomes as control, 1 wk before sensitization/challenge to Ole e 1. Blood, lungs, and spleen were collected and analyzed for immune responses. Intranasal administration of tolerogenic exosomes inhibited the development of IgE response, Th2 cytokine production, and airway inflammation—cardinal features of allergy— and maintained specific long-term protection in vivo. This protective effect was associated with a concomitant increase in the expression of the regulatory cytokine TGF-β. These observations demonstrate that exosomes can induce tolerance and protection against allergic sensitization in mice. Thus, exosome-based vaccines could represent an alternative to conventional therapy for allergic diseases in humans.

Ag 5 is a major allergen of vespid venom. The complete amino acid sequences of Ag 5 from two species each of hornets (Dolichovespula arenaria and maculata), wasps (Polistes annularis and exclamans), and yellow jackets (Vespula maculifrons and vulgaris) have been determined by amino acid sequencing and/or cDNA cloning. The sequence data reveal several conserved and variable regions for vespid Ag 5. The conserved regions show greater sequence similarity than do the less conserved regions to a family of proteins from human, mouse, and rat testis and to a class of pathogenesis-related proteins from tobacco and tomato leaves. Tests in the murine system for both T and B cell responses demonstrate a high degree of cross-reactivity of hornet Ag 5 with wasp or yellow jacket Ag 5 and a low degree of cross-reactivity of yellow jacket Ag 5 with wasp Ag 5. This pattern of cross-reactivity is in the same order as their sequence similarity.