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 (MUXF(3), 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 (>or=0.35 kU/l) IgE to peanuts, we performed inhibition assays with a neoglycoprotein consisting of MUXF(3) molecules coupled to bovine serum albumin (MUXF(3)-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 MUXF(3)-BSA, but not with MM-BSA. IgE binding to multiple bands on immunoblotting studies was also inhibited by MUXF(3)-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.