Cross-reaction

Allergological term, which plays an important clinical role especially in food allergies. Here, an allergen A induces a sensitization, due to which allergen B can trigger an allergic reaction. A cross-reaction is based on a similarity of molecular structures of different allergens (example: birch - apple).

• Significant cross-reactions between plant foods (mod. n. L. Hunter):
  • Birch (Bet v 1/2):
    • Fagale pollen: apple, pear, cherry, hazelnut, celery, carrot, parsley, pistachio, ( latex).
    • Raw vegetables: celery, carrot, tomato, pea.
    • Spices: coriander, basil, garlic, onion, chicory.
    • Fruit: apple, pear, cherry, strawberry, kiwi, orange, banana.
  • Mugwort:
    • Raw vegetables: celery, carrot, potato, pepper, tomato, cucumber, peanut.
    • Spices: aniseed, parsley, caraway, curry, cardamom, ginger, garlic, nutmeg, pepper, cinnamon.
    • Fruit: Melon, mango, kiwi, apple.
    • Pollen: birch.
  • latex:
    • Avocado, banana, potato, pepper, kiwi, peach, chestnut, buckwheat flour.
  • Significant cross-reactions between animal foods:
    • Tropomyosin: crustaceans (see below crustacean allergy), molluscs, house dust mite.
    • Parvalbumin (see below fish allergy)
    • Bird serum albumin and chicken serum albumin (see below bird-egg syndrome)

A cross-reaction is caused by an identical or related allergen. This is not surprising in the case of taxonomically related allergen sources (e.g. cereals/grasses; olive/lilac or peach/cherry/plum/apricot). It was shown that for cross-reactivity a sequence identity of > 50% is usually necessary (linear epitopes). Proteins with this degree of similarity have many identical sites on their surface that can act as potential epitopes for cross-reactive antibodies. Cross-reactions are also possible if the 3D structure is similar (conformation, conformational epitope).

Clinically surprising are cross-reactions in taxonomically unrelated structures ( tropomyosin and shrimp/house dust mite mite shellfish syndrome or alpha-livetin and bird-egg synd rome as well as cat-pork syndrome with sensitization to cat serum albumin and cross-reactivity to serum albumin in pork, alpha galactose as ubiquitous sugar in glycoproteins and glycolipids of all mammals but not in humans and various other mammals). monkeys).

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2. Jäger L, Wüthrich B (1998) Food allergies and intolerances. Gustav Fischer, Ulm Stuttgart Jena Lübeck 89-90
3. Kutting B et al (2001) House dust mite-crustaceans-molluscs syndrome. A rare variant of food allergy in primary sensitization to inhaled allergens. dermatologist 52: 708-711
4. Kleine-Tebbe J et al (2003) Cross-reactive allergen clusters in pollen-associated food allergy. dermatologist 54: 130-137
5. Weber RW (2003) Patterns of pollen cross-allergenicity. J Allergy Clin Immunol 112: 229-239