t8 Elm

Allergens within Tree Pollens

Print Print icon Tell a friend Tell a friend icon
  • Latin name: Ulmus americana
  • Family: Ulmaceae
  • Common names: White Elm, American Elm
  • Source material: Pollen
Related species:
  • U. americana - White Elm
  • U. glabra - Wych Elm
  • U. carpinifolia - Smooth Elm
A tree species producing pollen, which often induces hayfever, asthma and conjunctivitis in sensitised individuals.

Allergen Exposure

Geographical distribution
White Elm can be found mostly in forests in central and eastern North America, where it represents a major source of pollen. The corresponding European species, Wych Elm (U. glabra) and Smooth Elm (U. carpinifolia), are distributed or cultivated throughout the north temperate regions. In the 1930's, Dutch Elm disease devastated White Elm trees in North America as well as in Europe.
 
White Elm is a deciduous tree growing up to 40 m tall and is well known for its vase-shaped crown.  When growing in the open, the trunk divides near the base into several large limbs which arch outward, resulting in the vase-shaped silhouette.  The bark is furrowed and light- or dark-grey. The dark-green leaves are alternate, simple, and have doubly toothed margins. They are oval to elliptic and are 8 to 15 cm long, with a smooth or sand-papery surface. The underside is pale green.

The flowers appear in late winter or early spring as drooping, hairy, greenish-red clusters of 3 to 4 flowers, while other species of the genus flower in the fall. Oval and flat fruit are produced. These are up to 1.5cm long and have papery wings.
 
Environment
White Elm grows in woods and hedges and by roads and streams, occurring on moist upland sites and bottomlands. In bottomlands, the trunk is more likely to be buttressed than in the uplands. American Elm was widely planted as an ornamental in urban settings because it was stress-tolerant, fast-growing, and beautiful. Dutch Elm disease has made the tree rarer and less important. The wood is heavy and strong and is used in flooring.
 
Allergens
No allergens from this plant have yet been characterised.

Potential Cross-Reactivity

An extensive cross-reactivity among the different individual species of the genus could be expected as well as to a certain degree between members of the family Ulmaceae (1).

Clinical Experience

IgE mediated reactions
White Elm pollen can induce  asthma, allergic rhinitis and allergic conjunctivitis (2-3).   
 
The importance of Ulmaceae pollen in asthma, allergic rhinitis and other allergy conditions has been demonstrated by numerous studies from around the world. In Washington, DC, the Ulmaceae have been shown to have two distinct pollinating times, with the later-flowering species of Elm pollinating from August through October, coinciding with Ragweed season. April is usually the month with the highest weekly average concentrations (4).
 
Elm tree pollen has also been demonstrated to be an important aeroallergen in Salamanca, Madrid, and Badajoz, Spain (5-7), and in 9 districts of northern China (8). In one district, Elm pollen was the most dominant aeroallergen detected.
 
Elm tree pollen has also been shown to be an important aeroallergen in Tehran, Iran, where the pollen season extends from the first week of February through the middle of October (9).
 
In Siena, in central Italy, Elm tree pollen was found to be an important aeroallergen in March, but not during the rest of the tree pollen season (10), whereas in Modena, in northern Italy, the Elm family contributed little pollen to the air (about 1% of the total pollen recorded) (3). Similarly, Elm tree pollen was not shown to be an important aeroallergen in Missouri, USA (11). In Tampa, Florida, in the USA, where the major tree pollen season occurs from December through May, with a minor season occurring from October to November, Elm tree pollen is important during the minor season (12).
 
Specific IgE to Elm tree pollen was detected in pollen-allergic individuals with allergic rhinitis in Jena, Germany (2).
 
Other reactions
Delayed and prolonged contact urticaria as a result of contact with Elm tree has been reported (13).
 
Compiled by Dr Harris Steinman, harris@zingsolutions.com

References:

    1. Yman L. Botanical relations and immunological cross-reactions in pollen allergy. 2nd ed. Pharmacia Diagnostics AB. Uppsala. Sweden. 1982: ISBN 91-970475-09 
    2. Jung K, Schlenvoigt G, Jager L. Allergologic-immunochemical study of tree and bush pollen. II--Study of the sensitization spectrum of patients with seasonal rhinitis in the spring. [German] Allerg Immunol (Leipz) 1987;33(4):215-221 
    3. Torri P, Accorsi CA, Bandini Mazzanti M, Zagni AM. A study of airborne Ulmaceae pollen in Modena (northern Italy). J Environ Pathol Toxicol Oncol 1997;16(2-3):227-30 
    4. Kosisky SE, Carpenter GB. Predominant tree aeroallergens of the Washington, DC area: a six year survey (1989-1994). Ann Allergy Asthma Immunol 1997;78(4):381-392 
    5. Subiza J, Jerez M, Jimenez JA, Narganes MJ, Cabrera M, Varela S, Subiza E. Allergenic pollen pollinosis in Madrid. J Allergy Clin Immunol 1995;96(1):15-23 
    6. Silva Palacios I, Tormo Molina R, Nunoz Rodriguez AF. Influence of wind direction on pollen concentration in the atmosphere. Int J Biometeorol 2000;44(3):128-33 
    7. Hernandez Prieto M, Lorente Toledano F, Romo Cortina A, Davila Gonzalez I, et al. Pollen calendar of the city of Salamanca (Spain). Aeropalynological analysis for 1981-1982 and 1991-1992. Allergol Immunopathol (Madr)1998;26(5):209-22 
    8. Li WK, Wang CS. Survey of air-borne allergic pollens in North China: contamination with ragweed. N Engl Reg Allergy Proc1986;7(2):134-43 
    9. Shafiee A. Pahlavi. Atmospheric pollen counts in Tehran, Iran, 1974. Med J 1976;7(3):344-51 
    10. Murgia M, De Dominicis V, Cresti M. The pollen calendar of Siena (Central Italy). Allergol Immunopathol (Madr)1983;11(5):361-5 
    11. Lewis WH, Imber WE. Allergy epidemiology in the St. Louis, Missouri, area. III. Trees. Ann Allergy 1975;35(2):113-119 
    12. Bucholtz GA, Lockey RF, Wunderlin RP, Binford LR, Stablein JJ, et al. A three-year aerobiologic pollen survey of the Tampa Bay area, Florida. Ann Allergy 1991;67(5):534-40 
    13. Czarnecki D, Nixon R, Bekhor P, Mason G. Delayed prolonged contact urticaria from the elm tree. Contact Dermatitis 1993;28(3):196-197

2002



Further Reading