High frequency of IgE sensitization towards kiwi seed storage proteins among peanut allergic individuals also reporting allergy to kiwi

BACKGROUND: IgE sensitization to storage proteins from nuts and seed is often related to severe allergic symptoms. There is a risk of immunological IgE cross-reactivity between storage proteins from different species. The potential clinical implication of such cross-reactivity is that allergens other than the known sensitizer can cause allergic symptoms. Previous studies have suggested that kiwi seed storage proteins may constitute hidden food allergens causing cross-reactive IgE-binding with peanut and other tree nut homologs, thereby mediating a potential risk of causing allergy symptoms among peanut ant tree nut allergic individuals. The objective of this study was to investigate the degree of sensitization towards kiwi fruit seed storage proteins in a cohort of peanut allergic individuals. METHODS: A cohort of 59 adolescents and adults with peanut allergy was studied, and self reported allergies to a number of additional foods were collected. Quantitative IgE measurements to seed storage proteins from kiwi and peanut were performed. RESULTS: In the cohort, 23 out of the 59 individuals were reporting kiwi fruit allergy (39%). The frequency of IgE sensitization to kiwi fruit and to any kiwi seed storage protein was higher among peanut allergic individuals also reporting kiwi fruit allergy (P = 0.0001 and P = 0.01). A positive relationship was found between IgE levels to 11S globulin (r = 0.65) and 7S globulin (r = 0.48) allergens from kiwi and peanut, but IgE levels to 2S albumin homologs did not correlate. Patients reporting kiwi fruit allergy also reported allergy to hazelnut (P = 0.015), soy (P < 0.0001), pea (P = 0.0002) and almond (P = 0.016) to a higher extent than peanut allergic individuals without kiwi allergy. CONCLUSIONS: Thirty-nine percent of the peanut allergic patients in this cohort also reported kiwi fruit allergy, they displayed a higher degree of sensitization to kiwi storage proteins from both kiwi and peanut, and they also reported a higher extent of allergy to other nuts and legumes. On the molecular level, there was a correlation between IgE levels to 11S and 7S storage proteins from kiwi and peanut. Taken together, reported symptoms and serological findings to kiwi in this cohort of patients with concurrent allergy to peanut and kiwi fruit, could be explained by a combination of cross-reactivity between the 11S and 7S globulins and co-sensitization to the 2S albumin Act d 13.