The project concentrates on Prunoidea (peach, apricot, plum, cherry, almond), celery and hazelnut allergens. Patients were selected by double-blind, placebo-controlled food challenges (DBPCFC)). And their sera were used for immunological studies. A 9 kD peach allergen (Pru p1) was identified, purified, characterised and its full amino-acid sequence was obtained. Pru p1is a lipid transfer protein (LTP) and cross-reacts with plum, apricot, cherry, apple, pear and corn LTP allergens. The 9 kD apricot allergen has been characterised in the same manner, and that of the plum allergen is underway. The presence of the Pru p1 in commercial peach nectars was confirmed for the first time. A processing flow-sheet was defined to prepare hypoallergenic limpid juices and nectars from peaches. The major allergen of hazelnut, 18 kD, was identified, and found to cross-react with birch pollen. The 18 kD peach allergen was cloned, sequenced and expressed as recombinant protein (Cor a 1.0401, Gen Bank Acc. Z72439). The allergen binds IgE from 41/43 (95%) of patients with a positive challenge to hazelnut. The sera of 21 celery-allergic patients presented IgE to the 16-kD Api g 1 (59%), IgE to profilin at 14 kD (23%), and to >30kD CCD-containing bands (50%). Sensitisation to Api g 1 and celery profilin, Api g 4 was confirmed by immunoblotting with the recombinant allergens. All patients with IgE against Api g 1 were also sensitised to Bet v 2. Benefits of results 1 Demonstrate, by the use of DBPCFC, that celery, Prunoidea and hazelnut provoke allergy. 2 Recognition of a new class of cross-reactive allergens, i.e. lipid transfer proteins (LTP). 3 Preparing better standardised in vivo and in vitro methods for these allergenic sources. 4 Demonstrate that the major allergen of peach, Prup 1, is present in commercially-available foods and the possibility to denature it in foods.