MOLECULAR CHARACTERIZATION OF API-G-1, THE MAJOR ALLERGEN OF CELERY (APIUM-GRAVEOLENS), AND ITS IMMUNOLOGICAL AND STRUCTURAL RELATIONSHIPS TO A GROUP OF 17-KDA TREE POLLEN ALLERGENS

Individuals suffering from immediate hypersensitivity (type-I allergy) to a particular pollen frequently display intolerance to several food s of plant origin. In this respect, individuals sensitized to birch po llen and/or mugwort pollen frequently display type-I allergic symptoms after ingestion of celery. In this study, we expressed the major alle rgenic protein of celery, Api g 1, which is responsible for the birch- celery syndrome, in the form of a non-fusion protein. The open reading frame of the cDNA of Api g 1 codes for a protein of 153 amino acids w ith a molecular mass of 16.2 kDa and 40% identity (60% similarity) to the major allergen of birch pollen, Bet v 1. Furthermore, Api g 1 exhi bited similar characteristics to (a) two proteins in parsley induced b y fungal infection, (b) the major tree pollen allergens and (c) pathog enesis-related and stress-induced proteins in other plant species. The reactivity of recombinant Api g 1 with IgE antibodies present in sera from celery intolerant patients was comparable to that of the natural celery allergen. Cross-reactivity with Bet v 1 was proven by cross-in hibition experiments, which provides further support for the existence of the birch-celery syndrome and for the suggestion that allergies to some vegetable foods are epiphenomena to allergies caused by inhalati on of tree pollen.