Novel Cross-Reactivity Syndrome: Severe Allergy To Ingested Quorn (Mycoprotein) In A Mould-Allergic Adolescent

Cross-reactivities between aeroallergens and certain food allergens have long been recognised. The classical pattern is one of initial sensitisation to an inhalant allergen followed - usually years to decades later - by the development of a secondary food allergy, owing to shared common proteins such as the PR-10 proteins, profilins and lipid transfer proteins.(1) The most common aeroallergen-food allergen cross-reactivity syndrome is the pollen-food ('oral allergy') syndrome; this involves prior sensitisation to pollens (grass, weed or tree) and the later development of food allergy to certain fruits, vegetables and nuts. Prior sensitisation to natural rubber latex can also lead to the latex-fruit syndrome, in which the shared enzyme chitinase leads to cross-reactivity between latex products and certain tropical fruits. Rarer forms of aeroallergen-food allergen cross-reactivity include the 'cat-pork' syndrome (allergy to pork following a cat allergy, owing to a cross-reactive serum albumin) and the 'bird-egg' syndrome (a cross-sensitisation between bird allergens and egg yolk). Sporadic cases of the 'mould-mushroom' syndrome have also been described(2) in which patients with mould-spore hypersensitivity react to mushrooms, usually in their raw form. In this case report, we report on a South African schoolboy, known to be allergic to inhaled mould spores, who reacts with anaphylaxis to an ingested meat substitute containing mycoprotein ('mould protein'). The case illustrates the potential for novel cross-reactivity syndromes to develop as novel plant-derived 'meat-substitute' food allergens become more widely available and in vogue.