Characterization of Self-Reported Pollen Food Syndrome (PFS) in Birch Allergic Subjects Exposed to Birch Pollen in an Environmental Exposure Chamber (EEC) in Canada

Abstract

PFS is associated with birch allergy due to food and pollen allergen protein homology. There is little data on PFS comorbidity with birch allergy in Canada. These meta-analyses examined the frequency of self-reported PFS, PFS phenotypes and Total Symptom Scores (TSS) reported by birch allergic patients exposed to birch pollen in an Environmental Exposure Chamber (EEC). A total of 219 subjects with history of birch allergy, ≥Class II birch-specific IgE, SPT+, were studied during the fall/winter (out-of-season) and exposed to birch pollen (average 3500±500 pollen grains/m3) in an EEC for 6 hours, with TSS recorded every 30 minutes. Their PFS status was based on subject-reported PFS questionnaire and PI algorithm adapted from Skypala et al., 2011. Subject PFS was phenotyped with descriptive statistics and TSS recorded at baseline in the EEC (no drug treatment) was compared between PFS+ and PFS- using unpaired t-tests. Of the 219 subjects studied, 29% (64) were PFS+. The highest food allergy reported was Fruits/Vegetables (84.3%) then Nuts (53.1%) >Potatoes/Root Vegetables(10.9%) =Milk/Eggs/Chicken(10.9%) >Fish/Shellfish(7.8%)>Beansprouts/Salad Leaves/Herbs(4.7%) =Wheat/Other Cereals(4.7%)>Beans/Lentils/Chickpeas/Legumes(3.1%) =Other Food (3.1%). Within Fruits: Apple(71.4%) >Peach/Nectarine(52.4%) >Cherry (47.6%) >Pear(42.9%) >Plum(28.6%)>Mango/Tropical Fruit(23.8%) >Strawberry(19%) >Pineapple(14.3%). Within Nuts: Brazil(42.9%) =Walnut/Pecan(42.9%) >Cashew/Pistachio(33.3%)=Hazelnuts(33.3%) >Chestnut(19.0%)>Peanut(4.8%)=Sunflower Seeds(4.8%). Average TSS reported in the EEC by PFS+(10.3) was not different from PFS-(10.18) (p=.83). These analyses show that PFS and birch allergy comorbidity exists in approximately one third of the patients studied but that there was no difference in PFS+ subjects versus PFS- subjects in the level of allergy symptoms evoked when exposed to birch pollen in the EEC.