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.

Epidemiology

Sunflower seed allergy is rare and limited to case studies, although likely underreported. 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.

Occupational asthma (OA) is a major public health concern, and sunflower seeds are considered one of over 400 contributing allergens. 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.

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.

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”. 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. 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.

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

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.

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.

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.

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. Lipid transfer protein-mediated cross-reactivity with patients who are tomato allergic has also been described.