Identification of a polygalacturonase (Cup s 2) as the major CCD-bearing allergen in Cupressus sempervirens pollen
Résumé
As IgE glyco‐epitopes, also referred to as cross‐reactive carbohydrate determinants (CCDs), can share significant structural homologies between different plants, they are prone to extensive cross‐reactivity among allergen pollen extracts. Here, cypress pollen allergens, especially a polygalacturonase (PG), were further characterized using double one‐dimensional electrophoresis (D1‐DE). The presence of specific IgE directed against CCDs was investigated by bromelain IgE inhibition and concanavalin A binding assays using sera of cypress pollen‐sensitized patients. Our results showed that IgE reactivity to CCDs in Cupressus sempervirens pollen extracts is mainly related to bromelain‐type epitopes of a newly identified cypress PG. This glycoprotein has been further characterized through an immunoproteomic approach and officially indexed as Cup s 2 by the WHO/IUIS allergen nomenclature. Cup s 2 could thus be associated with the increased prevalence of IgE reactivity to cypress pollen extracts because of CCD interference.