Oleaceae pollinosis: a review.

In the Oleaceae family, the most allergenic pollen is produced by Olea europaea, the olive tree, which in the Mediterranean area has been recognized as one of the most important cause of seasonal respiratory allergy. The olive pollination season lasts from May to the end of June and sometimes causes severe symptoms (oculorhinitis and/or bronchial asthma). Olive pollinosis is quite rare in the form of monosensitization. Although adults are affected the most, olive sensitization can be recognized in children, too. However, it is not easy to be sure about the clinical relevance of allergic sensitization to olive, even in patients with positivity to this pollen, as results from allergological tests in vivo and/or in vitro, because positivity to Olea pollen is not equivalent to clinical responsibility, above all in patients without seasonal respiratory symptomatology. Studies on the allergenic content of O. europaea pollen are currently in progress. In Northern and Central Europe, where there are no olive trees, there are two commonly occurring genera of the Oleaceae family, namely Fraxinus and Ligustrum, but these have a low frequency of allergic sensitization. A fourth anemophilous member of the Oleaceae, Phillyrea, has a more regional distribution in some parts of the Mediterranean. Other nonanemophilous and usually not allergenic Oleaceae genera are Forsythia, Jasminum and Syringa.