Plant Allergens and Pathogenesis-Related Proteins

In the recent past a great number of proteins causing type 1 allergic reactions in humans have been isolated and characterised. The main sources containing allergens are plants, mites, fungal spores and insects. Plantderived allergens may either be taken in from the upper respiratory tract or they are present in a vast range of plant food causing food allergic reactions. Compared to the enormous amount of different plant proteins only a small number out of them are identified as a an allergen at present. Looking at the allergen encoding sequences, relationships by sequence similarity can be found quite frequently to a restricted number of plant protein families. Predominantly, these protein families are seed storage proteins, structural proteins and proteins involved in the defence-related system - pathogenesis-related proteins. In the following, a short overview of a number of pathogenesis-related protein families is presented in relation to the already known homologous plant allergens.