Immunoglobulin‐E Reactivity to a Glycosylated Food Allergen (Peanuts) Due to Interference With Cross‐Reactive Carbohydrate Determinants in Heavy Drinkers

Background:  N-glycans in plant and invertebrate glycoproteins can induce extensive IgE cross-reactivity therefore limiting the specificity of in vitro allergy tests. IgE sensitization to N-glycans (cross-reactive carbohydrate determinants, CCDs) may be increased in heavy drinkers, who therefore show IgE reactivity to aeroallergens, latex, and Hymenoptera venoms. The peanut, a CCD-bearing allergen, is the leading cause of severe food allergic reactions in many populations. Aim of the study:  To investigate the potential interference of CCDs with determinations of IgE to peanuts in heavy drinkers. Methods:  We determined IgE to peanuts and IgE to a CCD marker (MUXF3, the N-glycan from bromelain) in 41 heavy drinkers admitted to the hospital and 54 healthy controls. None of the participants reported symptoms of peanut allergy. In cases with positive (≥0.35 kU/l) IgE to peanuts, we performed inhibition assays with a neoglycoprotein consisting of MUXF3 molecules coupled to bovine serum albumin (MUXF3-BSA) and a similar neoglycoprotein lacking xylose and fucose (MM-BSA). In the same cases, we screened for IgE to a panel of recombinant nonglycosylated peanut allergens. SDS-PAGE immunoblotting and inhibition assays were performed in selected cases. Results:  The prevalence of positive IgE to peanuts was 22 and 3.7% in heavy drinkers and healthy controls, respectively (p < 0.001). Peanut-IgE positivity was closely related to the presence of IgE to CCDs. In most (8/9) heavy drinkers with positive IgE to peanuts, reactivity was inhibited by preincubation with MUXF3-BSA, but not with MM-BSA. IgE binding to multiple bands on immunoblotting studies was also inhibited by MUXF3-BSA preincubation. IgE to nonglycosylated recombinant peanut allergens was uniformly negative. Conclusion:  Heavy drinking is associated with clinically asymptomatic IgE reactivity to peanuts, a relevant food allergen, in relation to CCD interference.