Cross-reactivity

From a cross-allergy ( cross-reaction ) is then spoken when immunoglobulin E antibody, directed against a particular allergen in a given allergen source, see also other allergens in other allergen sources and thus can cause an allergic reaction even at contact with these other sources of allergens.

Immunology

The formed in allergic patients IgE antibodies recognize specific epitopes ( motifs) on the allergen an allergen source. Comes in another matter before a molecule that has similar epitopes, it may be that the IgE antibodies may also bind to these similar epitopes and also trigger an allergic reaction. One example is the oral allergy syndrome (OAS ) in birch allergic patients. Here you IgE antibodies against the major allergen in birch pollen, Bet v 1, directed to recognize a similar protein in apple, Mal d 1, according to Malus domestica, the scientific name of the apple culture. This means that birch pollen allergy may experience when eating apples allergic symptoms, such as swelling, redness and itching of the oral mucosa, although their original excessive immune response is not directed against the apple - antigen, but against the major allergen Bet v 1 in birch pollen.

Besides Bet v 1 in birch pollen, there are three more cross-reactive structures (proteins) together cause a large proportion of allergic cross-reactions.

Strength of the cross-reactions

The allergen content of foods, since they are biological products vary widely. It depends, among other things, the level of maturity of the variety, the region and the method of preparation. Considered immunologically takes the cross-reactivity to the similarity and number of reacting epitopes. As with all services of the immune system and the physical and mental state plays a role in the intensity of the cross-allergy.

Expiration of the allergic reaction

Cross-reactivity of allergens runs on three levels.

  • B cells: When an allergen, or the cross-reactive allergen can bind to membrane-bound IgE on B cells, the results in the activation of the B cell. This activation is also under other controls, such as cytokines.
  • T cells: T cells recognize allergens only in processed form, namely as peptides which are presented by MHC II molecules on antigen presenting cells. These T- cell epitopes are small (about 13 amino acids long) and linear. Cross-reactivity at this level results in the activation of allergen-specific T cells.
  • Mast cells and basophils: To induce immediate allergic -type reaction of membrane -bound IgE antibodies on mast cells or basophils have to be cross-linked. This means that cross-reactive allergens must offer at least two epitopes which can bind to the IgE antibodies good and stable enough to bring such a cross-linking materialize.

Known cross allergies

  • Pollen: hazel, alder, oak, beech, ash, celery / mugwort
  • Foods: almonds, carrots, nuts (especially hazelnuts, walnuts, Brazil nuts ), ( soy)
  • Fresh fruits such as pome fruit and stone fruit: apples, pears, peaches, apricots, blackberry, strawberry, raspberry, plum / prune, cherry, plum, nectarine, jackfruit,
  • Rare: Tomatoes ( raw), potatoes ( raw), herbs / spices, kiwi, lychee and avocado, celery
  • Many different spices
  • Pollen: spelled, barley, oats, millet, corn, rice, wheat
  • Grass: perennial ryegrass
  • Food: Cornmeal
  • Pollen: sweet vernal grass, timothy, orchard grass, ryegrass (→ pineapple)
  • Food: potatoes ( raw), soy peanuts ( legumes), peas, kiwi, tomatoes, cantaloupe, watermelon
  • Cereals: rye, oat, wheat, barley
  • Peppermint, herbs / spices
  • Pollen: Composite as chrysanthemums / daisies, birch, dandelion, chamomile, sunflower, ragweed ( ragweed )
  • Food: peppers, celery, carrot, potato, kiwi, cucumber, melon, artichoke, tomato, sunflower seeds, peanuts, lychee, mango, apple
  • Spices: anise, coriander, chili, dill, tarragon, fennel, ginger, chamomile, cardamom, garlic, cumin, nutmeg, paprika, pepper, peppermint, parsley, mustard, wormwood, lovage, cinnamon
  • Herbs: basil, marjoram, oregano, thyme
  • Pollen: birch, mugwort
  • Food: Carrot
  • Spices: anise, basil, dill, fennel, oregano, cumin, coriander, lovage, marjoram, thyme
  • Pollen: olive, lilac, privet, forsythia
  • Mite species: food mite
  • Crustaceans: crabs, crabs, shrimp, scampi, shrimp, crayfish, lobster
  • Other: red mosquito larvae ( the fish feed ), snails, clams (eg, oyster), cockroaches
  • Pollen: mugwort, ragweed ( ragweed ), timothy
  • Foods: bananas, avocados, papaya, kiwi, chestnuts / chestnut, fig, raw potatoes, passion fruit, celery, tomato, peach, buckwheat flour, pepper, mango, acerola
  • Other: weeping fig ( ficus benjamini ) ( roasted chestnuts )
  • Pollen: mugwort, birch, grasses
  • Foods: pineapple, apple, carrot, potato, rye flour, wheat flour
  • Other: Latex

Differentiation from pseudo-allergies and intolerances

From a cross-allergy is not spoken:

  • With food sensitivities or intolerances (these are often confused with a food allergy ). Here the reaction takes place on biogenic amines such as histamine, serotonin, tyramine
  • Causing, if other components of the food, for example, metals, an allergic reaction

Nutrition Tips

Cross allergies may or may not occur. For example, show about 70% of birch pollen allergy during consumption of various plant foods, such as apples, stone fruits, carrots, celery and soy -based products, sometime allergic reactions to these products.

Each diet is therefore previously discussed with a doctor to ensure a healthy and balanced diet. For more frequent complaints driving a combined complaint, nutritional and pollen diary can help to identify potential food allergies, which can then be encircled with an elimination diet on. Often it is then sufficient food to heat-treat (eg, microwave), switch to other varieties or to refrain from consuming in the pollen season.

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