IgE mediates allergic reactions to peanut; however, peanut-specific IgE (sIgE) levels do not always equate to clinical peanut allergy. Qualitative differences between sIgE of peanut sensitised but tolerant (PS) and peanut allergic (PA) individuals may be important.
To assess the influence of IgE characteristics on effector cell activation in peanut allergy.
A cohort of 100 children was studied. The levels of IgE to peanut and peanut components were measured. Specific activity (SA) was estimated as the ratio of allergen-sIgE to total IgE. Avidity was measured by ImmunoCAP with sodium thiocyanate. IgE diversity was calculated based on ImmunoCAP-ISAC (Immuno Solid-phase Allergen Chip) assays for 112 allergens or for 6 peanut allergens. Whole blood basophils and mast cell line Laboratory of Allergic Diseases 2 (LAD2) sensitized with patients’ plasma were stimulated with peanut or controls and assessed by flow cytometry.
SA to peanut (p<0.001), Ara h 1 (p=0.004), Ara h 2 (p<0.001), Ara h 3 (p=0.02) and Ara h 6 (p<0.001) and the avidity of peanut-sIgE (P<0.001) was higher in PA than in PS individuals. Diversity for peanut allergens was greater in PA individuals (p<0.001). All IgE characteristics were correlated with basophil and mast cell activation. Peanut SA (R=0.447) and PD (R=0.440) had the highest standardised β-coefficients in combined multivariable regression models (0.447 and 0.440, respectively).
IgE specificity, SA, avidity and peanut diversity was statistically different in PA and PS individuals. IgE Peanut SA and PD had the greatest influence on effector cell activation and could be employed clinically.

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