Sensitivity to Quorn mycoprotein (Fusarium venenatum) in a mould allergic patient

A 27 year old female civil servant presented with five episodes of peri-orbital, tongue, and neck angio-oedema with wheeze and shortness of breath. One of these episodes occurred a few minutes after eating a Quorn burger. She had a 20 year history of perennial sneezing, rhinorrhea, and itchy throat, occurring throughout the day and night, but no cough or wheezing. While on holiday in Mauritius she was asymptomatic. Twelve years previously, she had received six months of weekly injections of alternaria, cladosporium, helminthosporium, and stempylium as immunotherapy in France. She had no pets, but had noticed mould on her bedroom and bathroom windows.

Skin prick testing and specific IgE results suggested type 1 hypersensitivities to Quorn, Alternaria alternata, Aureobasidium pullulans, cat dander, and grass pollen (table 1). Scrapings from her bathroom and bedroom windows grew heavy growths of Cladosporium sphaerospermum, Rhodotorula sp, Aureobasidium pullulans, and fewer numbers of non-sporing mould (Mycology Reference Laboratory, Bristol, UK).

Table 1.

Allergy testing results

	Skin prick testing		Specific IgE
Allergen	Wheal (mm)	Flare	IU/ml	Grade
Grass pollen mix	3	++	ND	ND
Cat dander	4	++	ND	ND
Dermatophagoides pteronyssinus	0	–	ND	ND
Dermatophagoides farinae	0	–	ND	ND
Fresh Quorn mixed with saline	7	++	ND	ND
Alternaria alternata	2	+	4.1	3
Aspergillus fumigatus	1	–	0.4	1
Cladosporium herbarm	1	–	0.6	1
Aureobasidium pullulans	ND	ND	0.8	2

In the skin prick test histamine produced a 6 mm wheal and ++ flare, and saline produced a 0 mm wheal and no flare. Results were those seen 15 minutes after using ALK standardised lancets and skin prick test reagents. The specific IgE tests were performed by Sheffield Protein Reference Unit. When Quorn was used as the allergen a small piece of fresh quorn burger was mixed with saline, and a single drop of liquid from the mixture was put on the patient’s forearm as with the other skin prick reagents. No specific IgE was detected to two other fusarium species, F culmorium and F oxysporum. Alternaria alternata, Aspergillus fumigatus, and Cladosporium herbarm are reported to crossreact with Quorn. There was a heavy growth of Aureobasidium pullulans in the patient’s home (no tests available to other species isolated).

ND, not done.

The patient’s rhinitis symptoms improved with the regular use of long acting antihistamines, replacing her windows, and controlling humidity at home. She has tried to avoid fungally contaminated food and has had no further episodes of angio-oedema.

Quorn mycoprotein is produced by Marlow Foods Ltd, from the fungus Fusarium venenatum.^1,2 Approximately 1/140 000 consumers report adverse reactions after eating Quorn. Ten such complainants had negative skin prick tests to an aqueous extract of fresh Quorn.³ Thirty three Quorn production workers did not have high titres of IgE specific to Quorn, although six known mould allergic subjects did.³ This study suggested that the risk of sensitisation to Quorn was low, but that patients who were allergic to mould might react adversely to inhaled or ingested mycoprotein. Crossreactivity studies showed that Quorn shared multiple allergenic determinants with Aspergillus fumigatus, Cladosporium herbarum, and Alternaria alternata.³ Allergen preparations for skin prick testing and specific IgE tests are poorly standardised, and may differ in their potency as much as 200–3000 fold.⁴ The diversity of fungal allergens is a challenge for successful immunotherapy.

A reduction in occupational exposure to fungi may be achieved using helmets with filtered air (which may remove up to 98% of spores), improving ventilation, and controlling humidity. Fungi in dwellings generally have no specialised spore liberation mechanisms and largely depend on disturbance. Spore wall structure determines whether allergens are already available on the surface, and whether the spores can remain airborne.