Dictionary of Allergies .. white Ash, [(L) Fraxinus americana

white Ash, [(L) Fraxinus americana, (Ger.) Esche, (Fr.) Frine blanc, (Gr.) Φραξίνος ο Αμερικανικός. White ash is a deciduous tree up to 40 meters, native and rather common in Eastern North America from Canada to Florida and west to the Mississipi. It is found also in Europe. Fraxinus is a genus of about 65 species. Pollination occurs from April to May. The ash belongs to the same family as the olive tree (Olea europea) which causes hay fever and asthma in the Mediterranean area. It is expected a high degree of cross-reactivity among different species of the genus Fraxinus [1]. Ash tree (Fraxinus excelsior) is the main representative of the Oleaceae family in temperate zones.

Diagnosis of ash pollen allergy is made difficult due to (1) an overlapping pollinization period with Betulaceae, (2) non-inclusion in current diagnostic assays, and (3) some cross- reactivity with minor allergens from Betulaceae. Hrabina M, et al (2007) studied the calibration of an ash pollen in-house reference preparation (IHRP) in allergic patients in order to produce standardized products for diagnosis and immunotherapy purposes. The ash pollen IHRP was defined and molecularly characterized. Its successful standardization at 100 IR/ml in patients specifically sensitized to Fra e 1 allowed a skin reactivity-based calibration in properly diagnosed patients.

Such a standardized ash pollen extract is a reliable tool to support immunotherapy of ash pollen allergy [2].

1. Yman L. Botanical relations and immunological cross-reactions in pollen allergy. 2nd Ed. Revised and enalrged. 1982. Pharmacia Diagnostics AB, Uppsala, p. 23-27.

Hrabina M, Purohit A, Oster JP, Papanikolaou I, Jain K, Pascal P, Sicard H, Gouyon 2. B, Moingeon P, Pauli G, André C. Standardization of an ash (Fraxinus excelsior) pollen allergen extract. Int Arch Allergy Immunol. 2007;142(1):11-8. Epub 2006 Sep 29.