ALLERGIC SENSITIZATION TO NATIVE AND HEATED CELERY ROOT IN POLLEN-SENSITIVE PATIENTS INVESTIGATED BY SKIN-TEST AND IGE BINDING

The rates of sensitization and allergy to four birch pollen related pl ant foods were investigated in a group of 167 patients who were sensit ive to at least one kind of pollen and one particular food. Sensitivit y was concluded from a positive skin prick test or the determination o f specific IgE, whereas allergy was based on anamnestic data. The posi tivity fates 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, 10 0 degrees C) celery root was performed on 46 of these patients. At lea st one positive test result (either prick test or EAST) was obtained f or native celery in 36/46 (78%) and for heated celery in 20/46 (43%) o f these patients. Although the concordance between the EAST and the sk in test was very low, extended control experiments of both test proced ures revealed no evidence for nonspecificity. Immunoblot analyses of e xtract from native celery and sera of 60 patients with a positive EAST (class greater than or equal to 2, greater than or equal to 0.7 U/ml) for celery resulted in the following rates of IgE binding to known cr oss-reactive celery allergens: Api g 1:33%, celery profilin: 17%; mult iple bands most probably due to carbohydrate epitopes: 32%. The rate o f binding to other allergens was below 10%. Since these three importan t structures are also present in birch pollen, no allergen could be id entified as a candidate to mediate an exclusive celery/mugwort associa tion. Investigation of extract from native and heated celery by immuno blotting pointed to a high lability of Api g 1, whereas profilin and c arbohydrate epitopes appeared to be more resistant to heat. It has bee n 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 p articular kind of extract used, neither the EAST nor the skin test alo ne represents an appropriate diagnostic method for testing sensitizati on to celery.