Food allergies associated with birch pollen: comparison of Allergodip and Pharmacia CAP for detection of specific IgE antibodies to birch pollen related foods.

Sera from 42 patients sensitive to birch pollen were investigated in a pilot study with the new Allergodip screening dipstick for cross-reactive allergens (Allergopharma). The dipstick contained nine separate allergen pads with extracts from birch pollen, hazel pollen, alder pollen, apple, hazelnut, carrot, peach, mugwort pollen and celery root (celeriac), together with negative and positive controls. The results of the test were assessed visually and classified in Allergodip classes 0-4 and compared with the results from the Pharmacia CAP method and with the symptoms reported by the patients. The Allergodip method showed good reproducibility for color intensity and visual assessment. The correspondence between Pharmacia CAP and Allergodip was high for tree pollens (98-100%) and medium for mugwort pollen, celery, hazelnut and carrot (60-71%). Apple and peach showed only 24% and 42% concordance, respectively The sensitivity and specificity of Allergodip and Pharmacia CAP differed in regard to food symptoms. However, they were always within the range of earlier publications. As a consequence of this study, the manufacturer of Allergodip has improved the apple allergen extract by adopting a low temperature extraction procedure. Subsequent measurements with sera from 14 apple-allergic patients showed greatly improved concordance with both CAP measurements and symptoms (93% and 86%, respectively).