k84 Sunflower seed

k84 Sunflower seed Scientific Information

Type:

Whole Allergen

Display Name:

Sunflower seed

Route of Exposure:

Inhalation

Family:

Asteraceae

Species:

Helianthus annuus

Latin Name:

Helianthus annuus

Other Names:

Common sunflower, sunflower, wild sunflower, annual sunflower

Summary

The sunflower is a globally cultivated crop, and sunflower seed products are used to make oil for human consumption as well as animal feed. Sunflower seed allergy is considered rare and usually limited to individual case reports. Cases have been linked to occupational inhalation exposure and anaphylaxis has been reported following allergen ingestion. The molecular basis of allergenicity is incompletely understood. To date, a lipid transfer protein (Hel a 3) and 2S protein (Hel a 2S) have been implicated. Cross-reactivity with a diverse range of pollens, tree nuts and seeds has been described.

Allergen

Nature

The sunflower plant, Helianthus annuus, is part of the Asteraceae (Compositae) family, which has 23,600 recognized species and also includes the weed mugwort, a major weed allergen in Europe (Ukleja-Sokołowska, Gawrońska-Ukleja et al. 2016, Denisow-Pietrzyk, Pietrzyk et al. 2019). Originally from Central America, the sunflower is cultivated worldwide, with China, Russia, the Ukraine, France, the USA and Argentina being the major global producers (1). Human consumption of sunflower seeds, used as a source of flour for bread, was first described 3000-5000 years ago by native Americans. Sunflower is now one of the most widely cultivated sources to produce oil as well as being used as a livestock feed due to its high protein content (2).

Taxonomy

*Taxonomic tree of Sunflower (Helianthus annus) (3)*
Domain	Eukarytota
Kingdom	Plantae
Subkingdom	Viridiplantae
Infrakingdom	Streptophyta
Superdivision	Embryophyta
Class	Magnoliopsida
Superorder	Asteranae
Order	Asterales
Family	Asteraceae
Genus	Helianthus L.
Species	Helianthus annus

Epidemiology

Sunflower seed allergy is rare and limited to case studies, although likely underreported (4, 5). Results from the EuroPrevall project has estimated a prevalence of sensitization to sunflower seeds in 5 % of adults in Europe and 8.7 % in India although a high proportion of sensitized subjects appear to be tolerant to the allergen (2).

Occupational asthma (OA) is a major public health concern, and sunflower seeds are considered one of over 400 contributing allergens (6). A study of workers from the largest sunflower processing factory in Thrace region of Turkey reported that 23.5 % of workers in direct contact with sunflower seed were sensitized to it. (7).

Route of Exposure

Main

The primary route of exposure to allergens in the occupational context is by inhalation of sunflower seed particles, whereas regular exposure is via ingestion after sensitization through skin contact or inhalation(4, 8).

Clinical Relevance

The clinical history of occupational sensitization to sunflower seeds, one of 400 high molecular weight allergens encountered in the industrial setting, follows the clinical course described for OA or “Baker’s asthma” (6, 9). Patients typically have no prior history and develop typical clinical signs of coughing, wheezing, conjunctivitis and rhinitis, usually following a lag period of several months in the workplace. Clinical symptoms persist at the workplace and resolve after time away from it. Smoking and an existing atopy diagnosis increase the risk of OA (6). Usually, the most effective management is to remove the patient from the workplace. Significant lung function impairment and increased rates of allergic rhinitis and conjunctivitis was found in workers directly exposed to sunflower vs control in a sunflower processing plant (7).

Anaphylactic reactions were recorded in 3 out of 4 sunflower allergic patients after ingesting sunflower seeds (10).

A case study involved an anaphylactic reaction in a patient sensitized to a sunflower lipid transfer protein, after eating potato chips cooked in sunflower oil (11).

Molecular Aspects

Table adapted from Allergome.org (12)

Allergen name	Protein group (if known)	Size (kDa)
Hel a 2S/SFA-8/SSA	2S Albumin storage protein	12
Hel a 3	Lipid Transfer Protein	9
Hel a 3.0101	Lipid Transfer Protein	-
Hel a 4	Defensin	-

The molecular basis of sunflower seed hypersensitivity is yet to be fully described (10). Sunflower seeds are known to contain 11 storage albumins, although only Hel a 2S/SFA-8 has been investigated for allergenic properties to date. Hel a 2S is a 2S albumin, and together with Hel a 3, a non-specific lipid transfer protein, have been identified as allergens. (2).

Additional allergenic proteins have been described: Hel a 1 (34kDa, without a specific protein family described); Hel a 2 (a 14.7kDa Profilin) and Hel a 6 (a 42kDa pectatelyase) (4)).

Biomarkers of severity

Compared to nuts, sunflower seeds contain a significantly higher concentration of lipid-soluble lipoproteins, possibly including oleosins, which have been associated with severe allergic symptoms (5).

Cross-reactivity

Sunflower-sensitized IgE subjects can cross-react with other members of the Asteraceae family including Mugwort (Artemisia vulgaris) .. Hel a 2 , a profilin protein originating from sunflower pollen, is thought to mediate this cross-reaction (10).

Cross-reactivity between sunflower seeds and Brazil nuts, mustard and pistachio, all foods that contain 2S albumin, have been indicated from observations made on a series of case studies (4).

Partial IgE cross-reactivity between Hel a 3 and the non-specific lipid transfer protein in peanuts (Ara h 9), hazelnuts (Cor a 8) and walnuts (Jug r 3) has been demonstrated (10). Lipid transfer protein-mediated cross-reactivity with patients who are tomato allergic has also been described (13).

Compiled By

Author: RubyDuke Communications

Reviewer: Dr. Michael Thorpe

Last reviewed:February 2022

References

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Ukleja-Sokołowska N, Gawrońska-Ukleja E, Żbikowska-Gotz M, Bartuzi Z, Sokołowski Ł. Sunflower seed allergy. International Journal of Immunopathology and Pharmacology. 2016;29(3):498-503.
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Martín-Pedraza L, González M, Gómez F, Blanca-López N, Garrido-Arandia M, Rodríguez R, et al. Two nonspecific lipid transfer proteins (nsLTPs) from tomato seeds are associated to severe symptoms of tomato-allergic patients. Mol Nutr Food Res. 2016;60(5):1172-82