The role of skin prick test in diagnosis of cross –allergy

Background: Patients with birch pollen allergy frequently develop hypersensitive reactions to certain food e.g. apples, celery and carrots due to cross-reactivity reactivity between these allergens. These reactions result from the similarity of allergen proteins structure, which are sometimes unbound phylogenetically. The aim of this study was to investigate the role of cross-reactivity and the diagnostic value of skin prick test (using commercial and native extracts of allergens), total and specific IgE in diagnosis such kind of allergy.

Material and methods: Fifty eight patients at the age above 16 were included in the study. The clinical history and the positive result of the skin prick test with the birch extract were the condition for qualifications. Patients were divided into two groups. Patients included in the first group were birch allergic without any symptoms after eating food (23 persons). Patients in the other group had birch pollen allergy and they had reported clinical symptoms after eating foods such as: apple, celery, carrot, tomato, banana, peach, peanut and hazelnut. (35 persons). The skin prick tests with pollen and food commercial extract and with native food allergens were determined for all individuals.

Results: All patients showed positive skin prick test with other pollen allergen extracts. Particularly a high percentage of positive skin reaction was find for hazel (78,3% in the first group vs. 97,1% in the second group) alder (82,6% vs. 97,1%). Patients included in the first group had positive skin reaction more often for grass and cereals (61% vs. 48,6%) and poplar (30,4% vs. 11,4%). Patients from the other group were characterized by a significantly higher percentage of positive skin tests with weeds. Generally, skin prick tests with native allergens showed more positive skin reaction and a better agreement with clinical history than skin prick tests with commercial extracts.

Conclusions: The skin prick tests with native allergens seems to be the method of verifying and supplementing other diagnostic tests in patients with food allergy.