No abstract

Low-temperature, acetone powder extracts were prepared from mature fruit of 16 apple strains. SDS-PAGE and immunoblot analysis revealed great variation in the relative amounts of the 18-kDa apple allergen in these extracts. EAST (RAST) scores, measured with individual and pool sera from patients allergic to birch pollen and apples, ranged from 0.2 to 4.0 and were related to the relative amount of the 18-kDa protein. These findings were confirmed by ELISA-inhibition assays, dose-related histamine release, semiquantitative evaluation of immunoblots by absorption/reflection densitometry, and skin prick tests with extracts of Golden Delicious, Boskoop, and Jamba apples (corresponding to a high, low, and very low 18-kDa allergen content). Additional open oral challenge tests were performed with two apple-allergic patients and 15 and 16 apple strains. With all methods, the deduced allergenic potency decreased in the following order: Golden Delicious > Boskoop > Jamba. Therefore, we concluded that the IgE-binding potency of apple strains depends on the occurrence of the 18-kDa allergen.

No abstract

The rates of sensitization and allergy to four birch pollen related plant foods were investigated in a group of 167 patients who were sensitive to at least one kind of pollen and one particular food. Sensitivity was concluded from a positive skin prick test or the determination of specific IgE, whereas allergy was based on anamnestic data. The positivity rates for sensitization and allergy, respectively, were: apple, 93 and 84%; hazelnut, 90 and 78%; celery, 70 and 14%; carrot, 60 and 37%. Comparative testing by skin prick test and enzyme allergosorbent test (EAST) with extract from native and microwaved (750 W, 30 min, 100^oC) celery root was performed on 46 of these patients. At least one positive test result (either prick test or EAST) was obtained for native celery in 36/46 (78%) and for heated celery in 20/46 (43%) of these patients. Although the concordance between the EAST and the skin test was very low, extended control experiments of both test procedures revealed no evidence for nonspecificity. Immunoblot analyses of extract from native celery and sera of 60 patients with a positive EAST (class ≥ 2, ≥ 0.7 U/ml) for celery resulted in the following rates of IgE binding to known cross-reactive celery allergens: Api g 1:33%, celery profilin: 17%; multiple bands most probably due to carbohydrate epitopes: 32%. The rate of binding to other allergens was below 10%. Since these three important structures are also present in birch pollen, no allergen could be identified as a candidate to mediate an exclusive celery/mugwort association. Investigation of extract from native and heated celery by immunoblotting pointed to a high lability of Api g 1, whereas profilin and carbohydrate epitopes appeared to be more resistant to heat. It has been concluded that sensitization to celery in German patients is without clinical significance in the majority of cases, in contrast to other birch-pollen-related plant foods such as apple and hazelnut. For the particular kind of extract used, neither the EAST nor the skin test alone represents an appropriate diagnostic method for testing sensitization to celery.

This murine model might be a useful tool in the quality control of allergenic extracts. It combines properties of assays based on standardized antisera and of assays that consider IgE cross-linking properties.