g17 Bahia grass

Allergens within Grass Pollens

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  • Latin name: Paspalum notatum
  • Family: Poaceae (Gramineae)
  • Subfamily: Panicoideae
  • Tribe: Paniceae
  • Common names: Bahia Grass, Bahiagrass
  • Source material: Pollen
A grass species producing pollen, which often induces hayfever, asthma and conjunctivitis in sensitised individuals.

Allergen Exposure

Geographical distribution
Paspalum has about 400 species. P. notatum is native to southern Brazil, Uruguay, northern Argentina, and northwestern Paraguay, and is found in most Central and South American countries. It has been introduced as a turf and forage grass into East and West Africa, Australia, India, Japan, Mexico, and the southern and eastern United States.
 
Paspalum notatum is a sod-forming, deep-rooted, warm-season perennial grass. It spreads by short, stout, woody runners and by seed. The runners have many large, fibrous roots, which form dense, tough sods, even on drought-prone sandy soils. The leaf bases at the terminus of each rhizome usually have a purplish hue. The stems of P. notatum are ascending, usually ranging from 20 to 75 cm tall, and the dark green leaves are 4 to 10 mm wide and 6 to 25 cm long.
 
The inflorescences have 2 to several spicate branches 4-12 cm long, and each branch (or raceme) has 2 rows of spikelets, either paired or positioned with one slightly below the other. Flowering is between June and November in the Northern Hemisphere. (Bahia grass ripens progressively over the summer in the United States and at no time is all the seed mature.) Besides vegetative spread, some varieties can reproduce asexually by unfertilized yet viable seeds; the sexually reproducing varieties are wind-pollinated. The plant seeds prolifically during the summer.
 
Environment
Bahia grass is widely used for forage and for erosion control. It easily invades disturbed pastures, roadsides, and rights-of-way, but does not appear to invade intact, undisturbed, native systems.
 
Allergens
Multiple antigenic components have been detected but no allergens from this plant have yet been characterised (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 Poaceae. Cross-reactivity between Bahia grass (g17), Johnson grass (g10) and Maize pollen (g202) can be expected, as they are closely related through the subfamily Panicoideae (2-3).  
 
Martin et al. reported that Bahia grass shares allergenicity with Timothy, Meadow, Rye, Redtop, Meadow Fescue, and Sweet Vernal grass, but also possesses unique allergens(4). More recent studies have not been able to confirm cross-allergenicity between Bahia and Timothy grass (5-6).
  
Pollen extracts of two trees, Callistemon citrinis (Bottlebrush) and Melaleuca leucadendron (Melaleuca), as well as the grass Paspalum notatum (Bahia) were analyzed for antigenic and allergenic cross-reactivity. Clinical studies demonstrated that 81% of patients who were skin test-positive to at least one of the pollens were also positive to the other two. Sixty-three percent of allergic individuals studied showed a high correlation between skin test results and the number of IgE-binding components analysed by immunoblotting. These IgE-reactive components were detected in the molecular weight range of 29-66 kDa. Each patient's serum had a unique IgE-binding pattern, indicating heterogeneity of immune response; however, common major determinants were detected by a large percentage of the allergic patients' sera (1).

Clinical Experience

IgE mediated reactions
Bahia grass is a significant aeroallergen, which can induce asthma, allergic rhinitis and allergic conjunctivitis (6-7).
 
In a study in which 38 subjects were challenged (25 nasally, 13 bronchially) with Bahia grass pollen extract, a positive Bahia intradermal skin test predicted a positive challenge to Bahia in all (11/11) of the nasal challenges and 75% (6/8) of the bronchial challenges. Specific IgE antibodies to Bahia pollen were detected by conventional RAST (greater than or equal to 2+) in 82% (14/17) of subjects with positive challenges and in 5% (1/20) of subjects with negative challenges (6).
 
Various studies around the world have demonstrated the importance of Bahia grass as an aeroallergen. In a study conducted in New South Wales, Australia, an association between Bahia grass and asthma in children was demonstrated (8). In Cartagena, Colombia, 28% of 99 subjects with acute asthma were found to be sensitised to Bahia grass(9). In 100 Thai patients with allergic rhinitis, 16% were positive in skin tests to Bahia grass pollen (10). 
 
Aerobiological and clinical studies in Kuala Lumpur, Malaysia, have documented the importance of Bahia grass pollen in the exacerbation of asthma and allergic rhinitis (11).

Compiled by Dr Harris Steinman, harris@zingsolutions.com

References:

    1. Sweeney M, Hosseiny S, Hunter S, Klotz SD, Gennaro RN, White RS. Immunodetection and comparison of melaleuca, bottlebrush, and bahia pollens. Int Arch Allergy Immunol 1994;105(3):289-96 
    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. Yman L. Pharmacia: Allergenic Plants. Systematics of common and rare allergens. Version 1.0. CD-ROM. Uppsala, Sweden: Pharmacia Diagnostics, 2000. 
    4. Martin BG, Mansfield LE, Nelson HS. Cross-allergenicity among the grasses. Ann Allergy 1985;54(2):99-104 
    5. Hosen H. Bahia grass and Timothy grass did not have a cross reactivity by using a nasal and bronchial challenge. Ann Allergy 1990;65(6):496 
    6. Phillips JW, Bucholtz GA, Fernandez-Caldas E, Bukantz SC, Lockey RF. Bahia grass pollen, a significant aeroallergen: evidence for the lack of clinical cross-reactivity with timothy grass pollen. Ann Allergy 1989;63(6 Pt 1):503-7 
    7. Hensel AE Jr, Griffith RC. Clinical experiences with Paspalum notatum (Bahia grass): a new grass antigen. South Med J 1972;65(6):690-3 
    8. Bass DJ, Delpech V, Beard J, Bass P, Walls RS. Late summer and fall (March-May) pollen allergy and respiratory disease in Northern New South Wales, Australia. Ann Allergy Asthma Immunol. 2000 Nov;85(5):335-6. Ann Allergy Asthma Immunol 2000;85(5):374-81 
    9. Caraballo L, Puerta L, Fernandez-Caldas E, Lockey RF, Martinez B. Sensitization to mite allergens and acute asthma in a tropical environment. J Investig Allergol Clin Immunol 1998;8(5):281-4 
    10. Pumhirun P, Towiwat P, Mahakit P. Aeroallergen sensitivity of Thai patients with allergic rhinitis. Asian Pac J Allergy Immunol 1997;15(4):183-5 
    11. Sam CK, Kesavan-Padmaja, Liam CK, Soon SC, Lim AL, Ong EK. A study of pollen prevalence in relation to pollen allergy in Malaysian asthmatics. Asian Pac J Allergy Immunol 1998;16(1):1-4

2002



Further Reading