Allergen recognition patterns in walnut allergy are age dependent and correlate with the severity of allergic reactions

Publication date: Available online 30 January 2019

Source: The Journal of Allergy and Clinical Immunology: In Practice

Author(s): Barbara K. Ballmer-Weber, Jonas Lidholm, Lars Lange, Mariona Pascal, Claudia Lang, Sunhild Gernert, Jaime Lozano-Blasco, Nora Gräni, Caroline Guillod, Andrea Wangorsch, Kay-Martin Hanschmann, Bo Pontoppidan, Linda Tjäder, Joan Bartra, Stefan Vieths

Abstract

Background

Walnut is an important elicitor of food allergy in children and adults with a high rate of severe reactions. Multicenter studies using a common clinical protocol and a comprehensive allergen are lacking.

Objective

To investigate potential correlations between molecular sensitization patterns and clinical characteristics of walnut allergic patients.

Methods

91 walnut allergic subjects and 24 tolerant controls from Switzerland, Germany and Spain were included. Walnut allergy was established by food challenge in all but anaphylactic subjects. sIgE to walnut extract, rJug_r_1 (2S albumin), rJug_r_3 (nsLTP1), nJug_r_4 (11S globulin), rJug_r_5 (PR-10 protein), two vicilin fractions, profilin and CCD was determined by ImmunoCAP. A threshold of 0.10 kU_A/L was used for positivity.

Results

Sensitivity of sIgE to walnut extract was 87% and increased to 96% for the sum of all walnut components. sIgE to walnut extract and all walnut components, except rJug_r_5, was significantly higher in patients below 14 years of age at inclusion. Stratification by age at onset of walnut allergy led to similar results. All patients <14 years had severe reactions whereas 38% of patients >14 years were mild reactors. Severe reactors (n=70) had higher sIgE levels than mild reactors (n=21) to walnut extract (p<0.0001), rJug_r_1 (p<0.0001), nJug_r_4 (p=0.0003) and both vicilin fractions (p<0.0001), but not to Jug_r_3 and Jug_r_5.

Conclusion

Sensitization to walnut storage proteins is acquired in childhood and correlates with severe reactions. sIgE levels to storage proteins Jug_r_1, Jug_r_4 and vicilin fractions, but not to nsLTP and PR-10 proteins, correlate with systemic reactions to walnut.

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