IgE reactivity to Api g 1, a major celery allergen, in a Central European population is based on primary sensitization by Bet v 1.
BACKGROUND
Up to 70% of patients with tree pollen allergy display allergic symptoms when eating certain fruits and vegetables. Homologous proteins with allergenic features are present in a wide range of plant species and can cause allergic reactions.


OBJECTIVE
The aim of this study was to evaluate recombinant Api g 1, a major celery allergen, for in vivo and in vitro diagnosis of celery allergy in populations from Davos, Switzerland, and Montpellier, France.


METHODS
A group of patients with celery and birch pollen allergy from Davos was tested, and the results from those tests were compared with results from a group of patients allergic to celery from Montpellier. Skin prick tests were performed with a commercial celery extract, crude celery, and purified recombinant Api g 1. Quantitative and qualitative serology was done with natural and recombinant allergens by means of RASTs and immunoblotting.


RESULTS
Recombinant Api g 1 allowed accurate in vivo diagnosis of celery allergy in all patients from the Swiss group. RAST results with celery extract were negative in 8 of 24 patients; results of immunoblotting with celery extract were negative in 4 of 24 patients, and results of immunoblotting with recombinant (r)Api g 1 were negative in 8 of 24 patients. In the French group 11 of 12 patients had a positive skin reaction with crude celery extract, but only 2 patients reacted with rApi g 1. RAST results for celery were positive in 8 of 12 patients. In immunoblotting experiments 8 patient sera displayed IgE directed against various celery allergens, whereas no patients sera had rApi g 1-specific IgE.


CONCLUSIONS
Our results document that rApi g 1 allows accurate in vivo diagnosis only in areas where birch trees are common. In areas where no birch trees grow, primary sensitization takes place through different pollen allergens (eg, mugwort pollen). Moreover, it became evident that birch pollen and celery allergy are highly related in Central Europe, whereas in Southern Europe the mugwort-celery type is predominant.
Hoffmann-Sommergruber
K
K
Department of General and Experimental Pathology, University of Vienna, Vienna, Italy.
Demoly
P
P
Crameri
R
R
Breiteneder
H
H
Ebner
C
C
Laimer Da Camara Machado
M
M
Blaser
K
K
Ismail
C
C
Scheiner
O
O
Bousquet
J
J
Menz
G
G
D000328:Adult; D000485:Allergens / Q000276:immunology*; D000888:Antibodies, Anti-Idiotypic / Q000032:analysis; D052179:Antigens, Plant; D005260:Female; D005602:France; D006801:Humans; D007114:Immunization; D015151:Immunoblotting; D007073:Immunoglobulin E / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010940:Plant Proteins / Q000276:immunology*; D011852:Radioallergosorbent Test; D012882:Skin Tests; D013557:Switzerland
D000485:Allergens; D000888:Antibodies, Anti-Idiotypic; D052179:Antigens, Plant; C096695:Api g 1 protein, Apium graveolens; D010940:Plant Proteins; C026408:anti-IgE antibodies; C061312:Bet v 1 allergen, Betula; D007073:Immunoglobulin E