The quantity and quality of α-gal-specific antibodies differs in individuals with and without delayed red meat allergy

Abstract

Background

IgG to galactose-α-1,3-galactose (α-gal) are highly abundant natural antibodies (Ab) in humans. α-gal-specific IgE Ab cause a special form of meat allergy characterized by severe systemic reactions 3-7 hours after consumption of red meat. We investigated 20 patients who experienced such reactions and characterized their α-gal-specific IgE and IgG responses in more detail.

Methods

α-gal-specific IgE was determined by ImmunoCAP. IgE-reactivity to meat extract and bovine gamma globulin (BGG) was assessed by immunoblotting and ELISA, respectively. In some experiments, sera were pre-incubated with α-gal or protein G to deplete IgG Ab. α-gal-specific IgG_1-4 Ab in individuals with and without meat allergy were assessed by ELISA.

Results

In immunoblots BGG was the most frequently recognized meat protein. IgE- and IgG-binding to BGG was confirmed by ELISA and completely abolished after pre-incubation with α-gal. Neither the depletion of autologous α-gal-specific IgG Ab nor the addition of α-gal-specific IgG Ab from non-allergic individuals changed the IgE-recognition of BGG of meat-allergic patients. Meat-allergic patients showed significantly higher α-gal-specific IgG1 and IgG3 Ab than non-allergic individuals whereas the latter showed significantly higher levels of α-gal-specific IgG4 Ab.

Conclusion

Patients with delayed meat-allergy display IgE and IgG Ab that selectively recognize the α-gal-epitope on BGG. Their enhanced α-gal-specific IgE levels are accompanied by high levels of α-gal-specific IgG1 devoid of IgE-blocking activity. This subclass distribution is atypical for food allergies and distinct from natural α-gal-IgG responses in non allergic individuals.

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