w13 Cocklebur

Allergens within Weed Pollens

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  • Latin name: Xanthium commune
  • Family: Asteraceae
  • Common names: Cocklebur, Rough Cocklebur, Common Cocklebur
  • Source material: Pollen
A weed species producing pollen, which often induces hayfever, asthma and conjunctivitis in sensitised individuals.

Allergen Exposure

Geographical distribution
Cocklebur is native to Europe, Asia, southern Canada, and most of the United States, Mexico and Central America. Cocklebur is now found worldwide. Another species that is less common but widespread across North America is called Spiny Cocklebur (X. spinosum).
 
Cocklebur is an annual, grey-green plant, growing up to 1.5m. The plant's structure is coarse and bushy with stems that are erect, branched, and rigid, with purple or black spots, and very rough. The leaves are lobed, triangular or heart-shaped, coarsely toothed, borne on long stalks, and rough on both sides. Leaves are 5 cm to 35 cm long, and 2 to 20 cm wide.
 
Cocklebur flowers from July to October, and the seeds ripen from August to October. The flowers are monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and are pollinated by insects. The plant is self-fertilising. Male flowers are small and green and hidden at the top of the plant in round clusters. Female flowers occur in burs on short stalks at the base where the leaf axils meet the stem. Each bur contains two flowers. The male flowers drop quickly, while female burs persist, with 2 blackish achenes.
 
The fruit produced is an elliptic to egg-shaped two-chambered bur, 1 to 3.5cm long, and is covered with about 400 stiff, hooked spines. Two prickles that are longer and wider than the others project from the tip of the bur.
 
Environment
This weed is commonly found in cultivated fields, waste areas, run-down and abandoned pastures, and road ditches. It is poisonous during the two-leafed stage. The burs often become tangled in the fur of grazing animals, thus aiding distribution of the species. Both seeds and seedlings are toxic to livestock.
 
The seed may be  dried, ground into a powder, and mixed with cereal flours during the making of bread and biscuits.
 
Allergens
Cocklebur allergens have not yet been fully characterised. Xan Ib and Xan VIa have been isolated from Cocklebur pollen as the important allergenic components. Xan Ib was found to be devoid of carbohydrate and had a molecular weight of 103,000 daltons. Xan VIa was a glycoprotein of molecular weight 17,000 daltons. The carbohydrate moiety of Xan VIa was found to be associated with allergenicity (1).

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 Asteraceae (2). 
 
Similar antigenic determinants have been found between Short Ragweed and Giant Ragweed, Cocklebur, Lamb's Quarters, Rough Pigweed, Marsh Elder, and Goldenrod. Cocklebur and Giant Ragweed were highly potent in their ability to competitively bind to short ragweed IgE (3). 

Clinical Experience

IgE mediated reactions
Cocklebur pollen can induce asthma, allergic rhinitis and allergic conjunctivitis (4).
 
Common Cocklebur is an important cause of inhalant allergies in Turkey (4).
 
Other reactions
Cocklebur is a common cause of contact dermatitis (5-8).  
 
Compiled by Dr Harris Steinman, harris@zingsolutions.com

References:

    1. Jaggi KS, Gangal SV. Purification and characterization of allergens from Xanthium strumarium pollen. Mol Cell Biochem 1987;78(2):177-89 
    2. Yman L. Botanical relations and immunological cross-reactions in pollen allergy. 2nd ed. Pharmacia Diagnostics AB. Uppsala. Sweden. 1982: ISBN 91-970475-09 
    3. Perrick D, Stafford CT, Armstrong E, DuRant RH. Modification of the fluorescent allergosorbent test as an inhibition assay for determination of cross-reactivity among aeroallergens. J Allergy Clin Immunol 1991;87(1 Pt 1):98-103 
    4. Guneser S, Atici A, Cengizler I, Alparslan N. Inhalant allergens: as a cause of respiratory allergy in east Mediterranean area, Turkey. Allergol Immunopathol (Madr) 1996;24(3):116-9 
    5. Singhal V, Reddy BS. Common contact sensitizers in Delhi. J Dermatol 2000;27(7):440-5 
    6. Nandakishore T, Pasricha JS. Pattern of cross-sensitivity between 4 Compositae plants, Parthenium hysterophorus, Xanthium strumarium, Helianthus annuus and Chrysanthemum coronarium, in Indian patients. Contact Dermatitis 1994;30(3):162-7 
    7. Guin JD, Skidmore G. Compositae dermatitis in childhood. Arch Dermatol 1987;123(4):500-2 
    8. Menz J, Winkelmann RK. Sensitivity to wild vegetation. Contact Dermatitis  1987 Mar;16(3):169-73

2002