IgE to food allergens are highly prevalent in patients allergic to pollens, with and without symptoms of food allergy

Abstract

Serum samples from 274 patients allergic to one or more of three pollens (birch, grass, mugwort), from 36 patients allergic to cat and/or Dermatophagoides pteronyssinus but not to pollen and from 55 non-allergic controls, as well as 20 cord blood samples, were examined for specific IgE to six 'pollen-associated' food allergens by using a new sensitive assay (CAP). A questionnaire asking for reactions to food was also sent to all patients. In the pollen group, 111 patients (47%) were positive (> or = 0.71 kU/l) for a food allergen (392 positive tests). Of these, 92 were sensitive to apple, 68 to potato, 64 to carrot, 63 to celery, 61 to peach and 44 to melon. In the non-allergic group, no IgE to any of the food allergens tested was found, whereas in the group allergic to non-pollen allergens, only one individual had such an IgE. The CAP assay was found to be more sensitive than RAST for the allergens studied. A history of clinical reactions (oral symptoms in 67, rhinoconjunctivitis in 65, asthma in 42 and urticaria in 39) to the corresponding food allergen was reported mainly by patients with positive CAP. In conclusion, we found a high prevalence of IgE to some food allergens in patients allergic to pollen and the absence of such antibodies in the control groups. The new in vitro assay, being more sensitive than previous ones, indicated a high prevalence of food specific IgE in pollen allergic patients, which in many cases did not correspond to clinical symptoms of food allergy.

Plant Food Allergies: A Suggested Approach to Allergen-Resolved Diagnosis in the Clinical Practice by Identifying Easily Available Sensitization Markers

“…Virtually all birch pollen-allergic patients are positive on SPTs with many of these fresh fruits and vegetables [21], but only a proportion of them, in general those reporting severe respiratory allergy symptoms or showing the highest levels of birch pollen-specific IgE [22, 23], have food allergy. This is particularly evident for allergies to vegetables that are botanically distant from Rosaceae, like those of the Apiaceae [24].…”

Allergies to Cross-Reactive Plant Proteins

“…These epitopes (carbohydrate cross-reactive determinants) are often seen on glycoproteins from plant and invertebrate tissues and probably bring about false-positive results on in vitro IgE tests that check cross-reactivity [23, 24]. The functional difference between the peptidic epitopes and carbohydrate epitopes described above sometimes confuses the interpretation of in vitro IgE tests that are applied daily in the diagnosis of immediate-type allergies [19, 20, 21, 22, 23, 24]. …”

Oral allergy syndrome - determination of specific IgE

“…25% -30% of all Europeans, allergic to pollens, report for OAS after consumption of fresh fruits and vegetables. OAS affects mostly people sensitized to wood pollens (birch) and seldom people sensitized to grass pollens (5)(6)(7)(8).…”