Table of Contents

Whole Allergen

w18 Sheep sorrel

w18 Sheep sorrel Scientific Information

Type:

Whole Allergen

Display Name:

Sheep sorrel

Allergen code:

w18

Family:

Polygonaceae

Species:

Rumex acetosella

Route of Exposure:

Inhalation

Source Material:

Pollen

Latin Name:

Rumex acetosella

Other Names:

Common sheep sorrel, mountain sorrel, red sorrel, cow sorrel, sour weed, ﬁeld sorrel, small sorrel, sorrel, horse sorrel

WHO/ICD-11 code:

XM72E8

(ICD-11 is currently under implementation by WHO and the ICD-11 codes displayed in the encyclopedia may not yet be available in all countries)

Summary

Sheep sorrel (Rumex acetosella) is a perennial, wind-pollinated, and invasive plant that grows to a height of around 15-40 cm. A single sheep sorrel plant can produce approximately 400 million pollen grains. This plant is predominantly found along floodplains, grasslands, open pastures, roadsides, and under forest canopies. Sheep sorrel (Rumex acetosella) is considered a cosmopolitan species as it is adaptable to a wide range of climatic conditions. The pollination period for this species initiates from late spring and extends till early summer. No allergenic proteins from sheep sorrel pollen have been identified in the IUIS database. Sheep sorrel pollen upon exposure can trigger conditions like rhino-conjunctivitis, allergic rhinitis, and bronchial asthma. Rumex spp. (sorrel) pollen has been reported to exhibit cross-reactivity with grass pollens.

Allergen

Nature

Sheep sorrel (Rumex acetosella) is an invasive, perennial, wind-pollinated plant that can attain a height of about 15-40 cm. The leaves are typically 1-8 cm in length, varied shaped with a smooth texture. This plant is dioecious and possesses unisexual, reddish-yellow flowers. The seeds are achenes, around 1.5 mm (length), shiny red-brown and often found to be encased in a rough-textured, reddish-brown hull (1). The pollination period for Rumex species ranges from late spring to early summer. However, the pollination may intensify from late April until May and might continue till the summer period. A single sheep sorrel plant has been claimed to produce around 400 million pollen grains. This plant is an herb with an acrid taste attributed to the presence of oxalic acid. The seeds of this plant have been reported to be consumed by birds, whereas the leaves and the whole plant acts as a natural food source for deer and rabbits (2).

Habitat

Sheep sorrel is reported to be prevalent along roadsides, open pastures, grasslands, floodplains, and under forest canopies. This plant is predominantly found in temperate coastal regions. It can sustain severe climatic conditions like extreme cold winters and hot, dry summers and is known to be drought-tolerant (1). Sheep sorrel can grow in varying altitudes ranging from 4500 to 8700 feet (2). This plant can thrive in various soil conditions like silty loam, sandy loam, gravel, heavy clay, etc. It can even survive in acidic (like low pH of 4.7) soil with low fertility (1).

Taxonomy

Around 200 weed species belonging to the genus Rumex are claimed to be found in the temperate climate regions in the Northern Hemisphere. Twenty-four of these species have been reported to be prevalent in California, while 20 species in the North-eastern region (2).

Taxonomic tree of Sheep sorrel (3)
Domain	Eukaryota
Kingdom	Plantae
Phylum	Spermatophyta
Subphylum	Angiospermae
Class	Dicotyledonae
Order	Polygonales
Family	Polygonaceae
Genus	Rumex
Species	Rumex acetosella

Tissue

Pollens of species from the genus Rumex are spheroidal (22 - 30 µm in diameter) and either tetracolporate (consisting of 4 colpi) or stephanocolporate (consisting of >3 colpi). The walls of these pollen grains are tectate (sculptured), with tightly arranged columellae, of around 1.5 µm thickness. These pollen grains have a reticulate (net-like) surface containing grooves of varied sizes. Each of these grooves encases a tiny, ellipsoidal pore in the center (2).

To date (24-January-2021), no allergenic proteins from sheep sorrel pollen have been identified in the IUIS database (4).

Epidemiology

Worldwide distribution

Pollen from species belonging to the genus Rumex (like sheep sorrel) may induce conditions like allergic rhinitis (5).

A Taiwan-based study conducted on 419 patients with allergic rhinitis (AR) symptoms reported the prevalence of sheep sorrel pollen mediated positive skin test (SPT) among 9.1% (38/419) of patients from the study population (6).

A study conducted in the US reported sheep sorrel pollen as one of the inhalant (respiratory) allergens found in 6% (26/411) of the analyzed patient’s serum samples (7).

An Iran-based study conducted on 306 AR patients (12-62 years) revealed the prevalence of sheep sorrel pollen mediated positive SPT in 42.8% of the study population (8).

A study conducted in Poland on 1069 patients with hypersensitivity to weed pollen revealed positive SPT towards sheep sorrel pollen in 19% of the weed pollen allergic patients (9).

A Japanese study conducted on 151 patients reported a positive scratch test (SPT) towards sheep sorrel pollen among 9% of the study population (10).

Environmental Characteristics

Worldwide distribution

Sheep sorrel (Rumex acetosella) has been regarded as a cosmopolitan species due to its adaptability to various climatic conditions. This plant has been claimed to be a perennial herb native to be native to Europe and south-western Asia; currently prevalent in several countries including Canada, Australia, New Zealand, India, Japan, China, Indonesia, Korea, Philippines, Taiwan, Russia, Kazakhstan, South Africa, South America (Peru, Chile, Columbia), North America (United States, Mexico), Central America (Costa Rica, El Salvador, Ecuador), Greenland and some oceanic islands like South Georgia, Saint Helena, French Polynesia, Reunion, Falkland Islands, and South Sandwich Islands (1).

Route of Exposure

Main

The route of exposure for sheep sorrel pollen is through inhalation (7).

Clinical Relevance

Exposure to sheep sorrel pollen may induce conditions such as allergic rhinitis (6), bronchial asthma (9) and rhino-conjunctivitis (8).

Allergic rhinitis (AR) and allergic rhino-conjunctivitis (ARC)

A study conducted on 419 patients with AR symptoms (itchy eyes and nose, nasal obstruction, rhinorrhea, sneezing) revealed pollen allergen sensitization in 28.2% (118/419) of the study population. Positive SPT towards sheep sorrel pollen was reported in 9.1% of the patients from the study population. Additionally, sleep impairment (moderate to severe) caused by nasal symptoms (AR-mediated) was also reported by some patients (6).

A study involving 306 AR patients (12-62 years) reported ARC in 74% (226/306) and a history of allergy among 60% (184/306) of the patients. A prevalence of positive SPT towards sheep sorrel pollen was revealed to be 42.8% of the study population and 44.1% among the atopic group (8).

Asthma

A retrospective study conducted specific-IgE testing on asthmatic patients and reported sheep sorrel allergen sensitization in 13.7% (16/117) of patients with non-fungal sensitization and 32.7% (17/53) of patients with fungal sensitization (11).

A study involving 1069 patients showing hypersensitivity to pollen allergens (weed) identified bronchial asthma in 9.4% (101/1069) of patients from the study population. 19% of the patients were found to exhibit positive SPT towards sheep sorrel pollen (9).

Prevention and Therapy

Prevention strategies

Avoidance

During pollen season, allergic patients are suggested to stay indoors or wear a mask outdoors to keep away from pollen allergens. In worsening conditions, patients may be recommended to move or live in a non-pollen area (12)

Molecular Aspects

Allergenic molecules

As of 24^th January 2021, no allergenic molecules from sheep sorrel pollen have been listed in the IUIS database (4).

Cross-reactivity

Rumex spp. (sorrel) pollen allergens have been reported to be cross-reactive with grass pollens (13).

Compiled By

Author: Turacoz Healthcare Solutions

Reviewer: Dr. Christian Fischer

Last reviewed: March 2021

References

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Weber RW. Sheep sorrel. Ann Allergy Asthma Immunol. 2004;93(2):A6.
CABI. Rumex acetosella (Sheep's sorrel) - Invasive Species Compendium 2021 [22-January-2021]. Available from: https://www.cabi.org/isc/datasheet/48056.
WHO/IUIS. International Union of Immunological Societies Allergen Nomenclature 2021 [21-Jan-2021]. Available from: http://www.allergen.org/search.php?allergensource=roughmarshelder&searchsource=Search.
Weber RW. Allergen of the Month—Monk's Rhubarb. Annals of Allergy, Asthma & Immunology. 2015;115(4):A13.
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Fereidouni M, Hossini RF, Azad FJ, Assarezadegan MA, Varasteh A. Skin prick test reactivity to common aeroallergens among allergic rhinitis patients in Iran. Allergologia et immunopathologia. 2009;37(2):73-9.
Gniazdowska B, Doroszewska G, Doroszewski W. [Hypersensitivity to weed pollen allergens in the region of Bygdoszcz]. Pneumonol Alergol Pol. 1993;61(7-8):367-72.
Suzuki Y, Ohta N, Sakurai S, Aoyagi M, Fukase S. [Examination about positive ratio of pollen antigens by scratch test]. Arerugi. 2009;58(12):1619-28.
Medrek SK, Kao CC, Yang DH, Hanania NA, Parulekar AD. Fungal sensitization is associated with increased risk of life-threatening asthma. The Journal of Allergy and Clinical Immunology: In Practice. 2017;5(4):1025-31. e2.
Xie ZJ, Guan K, Yin J. Advances in the clinical and mechanism research of pollen induced seasonal allergic asthma. Am J Clin Exp Immunol. 2019;8(1):1-8.
Puc M. Characterisation of pollen allergens. Annals of Agricultural and Environmental Medicine. 2003;10(2):143-50.