Cross‐reactivity between olive and other species. Role of Ole e 1‐related proteins

Olive (Olea europaea) pollen is considered as one of the most important causes of respiratory allergic disease in the Mediterranean region. In Spain, it is the second cause of pollinosis after grass pollen (Table 1) (1). However, the epidemiological and clinical impact of olive pollinosis varies markedly from one area to the next since the pollen source, the olive tree, is a cultivated species and its distribution changes from one region to the next (2). Another relevant characteristic of the aerobiology of the olive pollen is the relative shortness and severity of the pollen seasons, although these follow a pattern of alternation due to a phenomenon called ‘Alternance of Production’ (2). The pioneering work on olive allergens started in the 1980s. In these studies the main allergen (currently known as Ole e 1) was found to be an acidic protein which appeared as a double band of about 17 and 19 kDa on SDS-PAGE (3,4). However, it was not until the 90s when the application of monoclonal antibodies and molecular biology techniques allowed to characterize up to nine different olive allergens. Some of the olive allergens identified have counterparts (homologue proteins) in other pollen sources: Ole e 1, Ole e 2 (profilin), Ole e 3 (polcalcin) and Ole e 7 (LTP) (Table 2).