t8 Elm

Allergens within Tree Pollens

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  • Latin name: Ulmus americana
  • Family: Ulmaceae
  • Common names: Elm, White elm, American elm
  • Source material: Pollen

Allergen Exposure

Geographical distribution

The Elm family, Ulmaceae, contains 6 genera, the most important being Ulmus, Planera, and Zelkova. (Hackberries [Celtis spp.] used to be included in the Elm family but are more closely related to Urticaceae and have been placed in a separate family, Celtidaceae).

There are about 45 species of Elms worldwide, found in the temperate Northern Hemisphere, with about 4 introduced species to the USA, and 6 native to North America east of the Rocky Mountains. There are 25 species of Ulmus (1-3).

White elm can be found mostly in forests in central and eastern North America, where it represents a major source of pollen. White elm is native to North America and has a wide range, from all of the eastern states through the Central Plains (4).

The corresponding European species, Wych elm (U. glabra) and Smooth elm (U. carpinifolia), grow wild or cultivated throughout the north temperate regions. In the 1930s, Dutch elm disease devastated White elm trees in North America as well as in Europe. The disease, a fungal blight, was caused by the ascomycete Ophiostoma ulmi and transmitted through the native Elm bark beetle, Hylurgopinus rufipes (5). All Elms are susceptible to some degree to the fungus, especially American elm (U. Americana) and September elm (U. serotina). Chinese elm (U. parvifolia), Siberian elm (U. pumila) and Red or Slippery elm (U. rubra) are highly or moderately resistant (1,3).

White elm is a deciduous tree growing up to 40 m tall and is well known for its vase-shaped crown. The bark is furrowed and light- or dark-grey. The dark-green leaves are alternate, simple, and have doubly toothed margins.

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 1.5 cm long and have papery wings.

Environment
White elm grows in woods and hedges and by roads and streams, occurring on moist uplands and bottomlands. In bottomlands, the trunk is more likely to be buttressed than in uplands. American elm was widely planted as an ornamental in urban settings because it was stress-tolerant, fast-growing, and beautiful. 

Allergens
No allergens 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 among members of the family Ulmaceae (6). However, to date this has not been documented.

In a Spanish study, individuals with Melon allergy were found to be especially prone to sensitisation and asthma to several tree and weed pollens, predominantly Ulmus and Ambrosia (7).

Clinical Experience

IgE mediated reactions
White elm pollen can induce asthma, allergic rhinitis and allergic conjunctivitis (8-9).

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 2 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 (10).

Elm tree pollen has also been demonstrated to be an important aeroallergen in Salamanca, Madrid, and Badajoz, Spain (11-13), and in 9 districts of northern China (22). In one district, Elm pollen was the 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 (14).

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 (15); whereas in Modena, in northern Italy, the Elm family contributed little pollen to the air (about 1% of the total pollen recorded) (9).

Similarly, Elm tree pollen was not shown to be an important aeroallergen in Missouri, USA (16). 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 (17).

In a New York study of 371 allergy patients tested serologically for hypersensitivity to prevalent tree pollens in the surrounding area, the highest rate of hypersensitivity was to Oak (34.3%), Birch (32.9%), and Maple (32.8%) tree pollens, with a rate of 24.6% for Elm being recorded (18). In a Canadian study that evaluated the impact of different trees on asthma, along with the association between daily hospitalisations for asthma and daily concentrations of different tree pollens in 10 large Canadian cities, it was reported that for an interquartile increase in daily tree pollen concentration, percent increases in daily hospitalization for asthma were 2.63% for Ulmus (19).

Aerobiology studies often do not draw distinctions among the various species of Ulmus, but this may not be problematic; considering the close relationship among these species, cross-sensitisation or cross-reactivity is possible. Pollen concentration in the atmosphere of Lublin (in eastern Poland) was reported to be the highest for Betula, Pinaceae and Alnus; and the lowest for Ulmus, Fagus and Corylus. Signficantly, total pollen grains for Ulmus varied almost 2-fold between successive years (20). Pollen from the Ulmus species has also been reported to be an important allergen in Zagreb, Poland (21). In aerobiology studies of 9 districts of northern China, the most common aeroallergens in spring were often Ulmus, Populus and Salix (22).

IgE antibodies to Elm tree pollen were detected in pollen-allergic individuals with allergic rhinitis in Jena, Germany (8).

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. Weber RW. Cedar elm.
      Ann Allergy Asthma Immunol 2006;96(4):A6
    2. Simpson BJ. A Field Guide to Texas Trees. Houston, Gulf Publishing Co., 1999:332–6
    3. Duncan WH, Duncan MB. Trees of the Southeastern United States. Athens, Georgia, University of Georgia Press. 1988:234-8
    4. Weber RW. American Elm (Ulmus americana) is a native tree that has had a wide range from the entire eastern states through the Central Plains.
      Ann Allergy Asthma Immunol 2001;86(2):A7
    5. Kendrick B. The Fifth Kingdom. Waterloo, Ontario, Canada, Mycologue Publications, 1985:55,178 –9
    6. Yman L. Botanical relations and immuno-logical cross-reactions in pollen allergy. 2nd ed. Pharmacia Diagnostics AB. Uppsala. Sweden. 1982: ISBN 91-970475-09
    7. Figueredo E, Cuesta-Herranz J, De-Miguel J, Lazaro M, Sastre J, Quirce S, Lluch-Bernal M, De las Heras M. Clinical characteristics of melon (Cucumis melo) allergy. Ann Allergy Asthma Immunol 2003;91(3):303-8
    8. 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):215-21
    9. 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
    10. 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):381-92
    11. 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
    12. Silva Palacios I, Tormo Molina R, Nunoz Rodriguez AF. Influence of wind direction on pollen concentration in the atmosphere.
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    13. 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
    14. Shafiee A. Pahlavi. Atmospheric pollen counts in Tehran, Iran, 1974.
      Med J 1976;7(3):344-51
    15. Murgia M, De Dominicis V, Cresti M.
      The pollen calendar of Siena (Central Italy). Allergol Immunopathol (Madr)1983;11(5):361-5
    16. Lewis WH, Imber WE. Allergy epidemiology in the St. Louis, Missouri, area. III. Trees.
      Ann Allergy 1975;35(2):113-9
    17. 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
    18. Lin RY, Clauss AE, Bennett ES. Hypersensitivity to common tree pollens in New York City patients.
      Allergy Asthma Proc 2002;23(4):253-8
    19. Dales RE, Cakmak S, Judek S, Coates F.
      Tree pollen and hospitalization for asthma in urban Canada.
      Int Arch Allergy Immunol 2008;146(3):241-7
    20. Weryszko-Chmielewska E, Piotrowska K. Airborne pollen calendar of Lublin, Poland. Ann Agric Environ Med 2004;11(1):91-7
    21. Peternel R, Culig J, Mitić B, Vukusić I, Sostar Z. Analysis of airborne pollen concentrations in Zagreb, Croatia, 2002
      Ann Agric Environ Med 2003;10(1):107-12
    22. Li WK, Wang CS. Survey of air-borne allergic pollens in North China: contamination with ragweed.
      N Engl Reg Allergy Proc 1986;7(2):134-43
    23. Czarnecki D, Nixon R, Bekhor P, Mason G. Delayed prolonged contact urticaria from the elm tree.
      Contact Dermatitis 1993;28(3):196-7

2008



Further Reading