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Whole Allergen

g4 Meadow fescue

g4 Meadow fescue Scientific Information

Type:

Whole Allergen

Display Name:

Meadow fescue

Route of Exposure:

Airway

Family:

Poaceae (Graminae)

Species:

pratensis

Latin Name:

Festuca pratensis

Other Names:

Festuca elatior, Lolium pratense, Festuca arundinacea

Summary

Fescue (genus Festuca), is a large genus of grasses belonging to the family Poaceae. Festuca pratensis (F. pratensis, Meadow fescue) native to Eurasia, is a perennial grass and commonly found in temperate and cold regions of Alaska to Nova Scotia, Europe, and the United States. Meadow fescue grass is used as forage, turf, and soil stabilization. The primary allergen of Meadow fescue is a pollen grain, which is monoporate, spheroidal to ovoid, with a diameter of 31-40 mm. It is reported to induce allergic rhinitis, allergic conjunctivitis, and asthma in sensitized individuals when exposed through oral or nasal route, which was evident from various studies. Meadow fescue grass consists of the following allergen molecules Fes p 1, Fes p 4, Fes p 5, and Fes p 13, which belong to the allergen groups 1, 2/3, 4, and 5. In-vitro diagnostic tests and skin prick test is recommended for Meadow fescue allergen by the World Allergy Organization (WAO) and European standards. Meadow fescue allergen immunotherapy is administered subcutaneously at an effective maintenance dose of 1000-4000 bioequivalent allergen units (BAU). Meadow grass has extensive cross-reactivity among the family Poaceae, particularly within the subfamily Pooidea.

Allergen

Nature

Meadow fescue is a perennial grass with a height of 50 to 120 cm, with an erect branched panicle or nodding (10-20 cm long). Leaf blades are wide (4-8 mm) and flat. Spikelets are lance shaped, with a length of 8-12 mm. The pollen grains of Meadow fescue are spherical to ovoid in shape with a diameter of 31-40 µm (1). 

Habitat

Meadow fescue is found in temperate regions, native to northern Europe and the United States. Ideally, it grows in open and damp places e.g. roadsides and waste places. It is a valuable pasture grass, but currently less planted (1).

Taxonomy

Timothy grass belongs to the phylum Spermatophyta, class Monocotyledonae, and subfamily Pooidaea (2). The genus Phelum consists of 15 species, among them P. pratense is the most extensively cultivated species (18). The two commonly recognized varieties are: i) P. Pratense var. pretense, ii) P. Pratense var. nodosum (18).

Taxonomic of Meadow fescue (1)    
Domain Eukaryota
Kingdom Plantae
Family Poaceae
Subfamily
Pooidaea
Genus Festuca
Species Festuca pratensis 
Taxonomic of Meadow fescue (1)    

 

Tissue

Pollen size: 36 (32.3-38.4) μm (medium).

Pollen class: 08 Monoporatae, 8.2. Poaceae.

Pollen grains are monoporate, spheroidal to ovoid, diameter of 31-40 mm, circular germinal pore of 2.5-4.5 mm diameter with a wavy margin, found at the larger end. Operculum has a diameter of 1.5- 2.0 mm with an irregular outline. The surface structure is fine but markedly granular (1).

 

Epidemiology

Risk factors

Meadow fescue pollen commonly induces allergic rhinitis (AR), allergic conjunctivitis (AC) and asthma in sensitized individuals (2). 

Environmental Characteristics

Worldwide distribution

Meadow fescue is native to Eurasia, introduced as a valuable forage grass in the USA and southern Canada, however, currently less planted. Meadow fescue is found from Alaska to Nova Scotia, Europe, and the United States (except Arizona and much of Florida). It is found in meadows, roadsides, and waste places (1). 

Route of Exposure

Main

Meadow fescue pollen grains are airborne and can enter the airway through the nasal or oral passage and triggers allergic reactions(2).

Clinical Relevance

Allergic rhinitis

Various studies (therapeutic and/or diagnostic) have mentioned about Meadow Fescue grass sensitized or allergic patients.  A Polish study examined specific IgE in 5 grass and 3 weed pollens in 22 seasonal AR patients aged between 13 and 53 years. The study found out that Meadow fescue was the most common sensitization followed by Meadow grass, and Cocksfoot (2). Similarly, a study in Norway found that Meadow fescue is a very important causative factor for allergic symptoms in 770 seasonal and perennial nasal symptoms patients. (3). In Yugoslavia, Meadow fescue pollen grains were reported as a frequent cause of allergic reactions (4).

Other diseases

The endophyte Neotyphodium coenophialum, in Fescue grass and grains, produces several classes of plant/fungal alkaloids. These pyrrolizidine alkaloids can be found in cow’s milk, which may possess a risk to children ingesting milk. (5, 6). The fungal alkaloid may lead to toxicosis which can manifest as vascular and thermoregulatory disturbances leading to local (fescue foot)  or general hyperthermia (summer fescue toxicosis). Also, it has been reported to induce reproductive problems, agalactia (failure of milk secretion), change in lipid metabolism with fat necrosis (lipomatosis), and increased oxidative stress (6).

Prevention and Therapy

Allergen immunotherapy

Allergen immunotherapy (AIT) improves AR symptoms and medication use in patients with or without conjunctivitis and allergic asthma. AIT is administered as subcutaneous immunotherapy (SCIT) or sublingual immunotherapy through drops or tablets. The potential effective doses for SCIT maintenance of Meadow fescue grass is found to be 1000-4000 bioequivalent allergen units (BAU)(7). In grass-sensitive individuals, recombinant Dac g II was recognized by species- and group-cross-reactive human IgE antibodies in 33% (4/12) of sera randomly selected from grass-sensitive individuals and in 67% (14/21) of sera from patients receiving grass pollen immunotherapy (8).

Prevention strategies

Following actions, can be taken to reduce allergic reactions to pollen:

  • Limit outdoor activities (if possible) during pollen season: This will reduce the amount of inhaled pollen allergen and will help in reducing allergic symptoms.
  • Keep windows closed during the pollen season.
  • Take allergy medicine before pollen season: this helps in preventing the release of histamine and other chemicals that can cause allergic reactions.
  • Wear sunglasses and a hat to keep pollen out of the eyes and hair.
  • Wash and dry clothes are worn during outdoor activities (9).

 

 

Molecular Aspects

Allergenic molecules

Grass spp. among Pooideae family have a significant affinity for groups of major allergen 1, 2/3, 4, and 5 (1). Overall, 24 allergens are identified from Meadow fescue, among which 12 have an affinity for binding with IgE antibodies in sera from patients with well-established AR.

  • Fes p 1.
  • Fes p 4 (60 kDa protein), Group 4 grass allergen, a berberine bridge enzyme.
  • Fes p 5, Group 5 grass allergen, a ribonuclease.
  • Fes p 13, Group 13 grass allergen, a polygalacturonase (10)

Meadow fescue grass contains Group 1 and 4 allergens:

Group 1 allergens 

  • Highly cross-reactive glycoproteins
  • Highly homologous, but not all of the antigenic epitopes are crossreactive
  • >95% of allergic patients possess IgE antibodies for Group 1 allergen (11).

Group 4 allergens 

  •  Glycoproteins
  • Molecular weight of 50 to 60 kDa

Around 75% of allergic patients possess IgE reactivity to Group 4 allergen(12)

Cross-reactivity

An extensive cross-reactivity exists among the family Poaceae, particularly within the subfamily Pooideae. Pooideae grasses lack group 2 and 5 allergens in members of the PACC clade, cross-reactivity is much less with southern grasses such as Bermuda and Bahia (1). Fescue meadow pollen cross-sensitizes with kiwi fruit. Kiwi glycoprotein (24 kilodaltons) is reported to have common epitopes and cross-reactivity with Meadow Fescue allergen (Fes p 4 and a 36 kDa) (4).

Other topics

DNA content of F. pratensis

 A study by Ebrahimzadegan R et al. (2019) concluded that repetitive sequences and transposable elements were observed in 61% of the genome, and 4% is satellite repeats which were partly harnessed as cytological markers. In the future, B-specific tandem repeats can trace the dynamics of supernumerary chromosomes which can provide direct insight into the cellular basis of the B chromosome drive mechanism in F. pratensis. (13).

Compiled By

Author: Turacoz Healthcare Solutions

Reviewer: Dr. Fabio Iachetti

 

Last reviewed: October  2020

References
  1. Weber. Allergen of the Month—Meadow Fescue. Annals of Allergy, Asthma & Immunology 113(1): A11. 2014.
  2. Silny W, Kuchta D, Siatecka D, Silny P. [Antigen specific immunoglobulin E to grass and weed pollens in the plasma of patients with seasonal allergic rhinitis]. Otolaryngol Pol. 1999;53(1):55-8.
  3. Holopainen E, Salo O, Tarkiainen E, Malmberg H. The most important allergens in allergic rhinitis. Acta Oto-Laryngologica. 1978;86(sup360):16-8.
  4. Gavrovic-Jankulovic M, Cirkovic T, Burazer L, Vuckovic O, Jankov RM. IgE cross-reactivity between meadow fescue pollen and kiwi fruit in patients' sera with sensitivity to both extracts. J Investig Allergol Clin Immunol. 2002;12(4):279-86.
  5. Panter KE, James LF. Natural plant toxicants in milk: a review. J Anim Sci. 1990;68(3):892-904.
  6. Haschek. Haschek and Rousseaux's handbook of toxicologic pathology. Academic Press. 2013.
  7. Calderon MA, Waserman S, Bernstein DI, Demoly P, Douglass J, Gagnon R, et al. Clinical Practice of Allergen Immunotherapy for Allergic Rhinoconjunctivitis and Asthma: An Expert Panel Report. J Allergy Clin Immunol Pract. 2020.
  8. Roberts AM, Van Ree R, Cardy SM, Bevan LJ, Walker MR. Recombinant pollen allergens from Dactylis glomerata: preliminary evidence that human IgE cross-reactivity between Dac g II and Lol p I/II is increased following grass pollen immunotherapy. Immunology. 1992;76(3):389-96.
  9. Cipriani F, Calamelli E, Ricci G. Allergen Avoidance in Allergic Asthma. Front Pediatr. 2017;5:103.
  10. Chang C. Definition of Allergens: Inhalants, Food, and Insects Allergens. Allergy and Asthma Springer, Cham https://doiorg/101007/978-3-319-58726-4_3-1. 2019.
  11. Kliene-Tebbe. Grass pollen allergens. . Global atlas of allergy, European Academy of Allergy and Clinical Immunology (EAACI): 22-26. 2014.
  12. Fischer S, Grote M, Fahlbusch B, Muller WD, Kraft D, Valenta R. Characterization of Phl p 4, a major timothy grass (Phleum pratense) pollen allergen. J Allergy Clin Immunol. 1996;98(1):189-98.
  13. Ebrahimzadegan R. Repetitive DNA landscape in essential A and supernumerary B chromosomes of Festuca pratensis Huds. Sci Rep 9, 19989 (2019) https://doiorg/101038/s41598-019-56383-1. 2019.