Allergens clinical cross-reactivity

Solid evidence exists to indicate that tropomyosins are pan-allergen among invertebrate species (Reese et ah, 1999). However, nontropomyosin allergens also exist in at least some species of molluscan shellfish. The clinical picture of cross-reactivity is more complex than might be anticipated. 

Nevertheless, cross-reactive IgE antibodies may cause positive SPTs without clinical symptoms, e.g., in the pollen-fruit syndrome, and thus reduce specificity. Nowadays, only recombinant food allergens of pharmaceutical grade can be applied for SPTs which means reproducible production criteria under Good Manufacturing Practice (GMP) guidelines. 

Even though IgE cross-reactivity among crustaceans and mollusks are commonly reported until recently, limited work has been done on the molecular identity of these cross-reactive allergens. The amino acid sequence identity with shrimp tropomyosin is fairly low with 57% and 61% for mussels and abalone, respectively (Figure 9.1). The relationship of molecular cross-reactivity with clinical reactivity has however not been adequately defined. 

Clinical relevant cross-reactivity between crustacean and house dust mite allergens has been described (Witteman et al. 1994) and the term mite-crustaceans-mollusk-syndrome is sometimes used. The primary sensitization is believed mostly to be respiratory allergy to dust mites, which then sometimes causes food allergic reactions to crustaceans or mollusks in some individuals. However, there are also observations on allergy to mites or cockroaches possible occurring subsequent to... 

Leung, P.S.C., Chow, W.K., Duffey, S., Kwan, H.S., Gershwin, M.E., Chu, K.H. 1996. IgE reactivity against a cross-reactive allergen in Crustacea and mollusca Evidence for tropomyosin as the common allergen. Journal of Allergy and Clinical Immunology 98(5) 954—961. 

Several authors report coexisting clinical soy allergies in 5%-50% of patients with cows milk allergies (NDA Opinion 2004). It is unclear whether soy allergy represents a de novo sensitization or a cross-reaction of a soy protein component with caseins from milk (Rozenfeld et al. 2002). However, due to homology in the amino acid sequences of soybean and cow s milk allergens of 50%-70%, cross-reactivity is likely (Wilson et al. 2005). 

The 2S albumin family is an important class of common allergenic proteins in seeds. Their presence in almost all edible seeds must be taken into account because of the high incidence of possible clinical reactions occurring in sensitized people and because of the actual possibility of cross-reactivity among different proteins of the same class. 

Sicherer, S.H. 2001. Clinical implications of cross-reactive food allergens. J Allergy Clin Immunol 108 881-890. 

Although exposure of most people to Psilocybe spp. is undoubtedly minimal, skin test reactivity to P cubensis spore extracts is the most significant of all basidiomycetes tested in Europe and the USA [20, 21]. This reactivity probably results from exposure to related species. P cubensis occurs naturally on the northeastern coast of South America, the Caribbean and the southeastern coast of North America. Although related species occur throughout the temperate northern hemisphere, the distribution of these mushrooms is probably less important clinically than the cross-reactivity patterns of its allergens. Several species in genera closely related to Psilocybe are common lawn... 

Reider, N., Sepp, N., Fritsch, P., Weinlich, G., and Jensen-Jarolim, E. 2000. Anaphylaxis to chamomile Clinical features and allergen cross-reactivity. Clin. Exp. Allergy 30, 1436-1443. 

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