Cross allergy

From a cross-allergy (also cross-reaction called) is then spoken when immunoglobulin E - antibodies directed against a specific allergen are directed in a particular allergen source, recognize other allergens in other allergen sources and thus also in contact with these other sources of allergens an allergic reaction can trigger.

immunology

The IgE antibodies formed in allergy sufferers recognize certain epitopes (motifs) on the allergens of an allergen source. If a molecule with similar epitopes occurs in another matter , it is possible that the IgE antibodies can also bind to these similar epitopes and also trigger an allergic reaction. One example is the oral allergy syndrome (OAS) in birch allergy sufferers. Here IgE antibodies directed against the main allergen in birch pollen, Bet v 1 , can recognize a similar protein in apples, Mal d 1 (after Malus domestica, the scientific name of the cultivated apple ). As a result, birch pollen allergy sufferers can experience allergic symptoms such as swelling, reddening and itching of the oral mucosa when consuming apples, although their original excessive immune response is not directed against the apple antigen , but against the main allergen Bet v 1 in birch pollen.

In addition to Bet v 1, there are three other cross-reactive structures (proteins) in birch pollen , which together cause the majority of allergic cross-reactions.

Strength of cross-reactions

The allergen content of foods can fluctuate greatly because they are organic products. It depends among other things on the degree of ripeness, the variety, the region and the method of preparation. From an immunological point of view, the cross-reactivity increases with the similarity and number of reacting epitopes. As with all activities of the immune system, the physical and mental condition also play a role in the intensity of the cross allergy.

Course of the allergic reaction

Cross-reactivity of allergens occurs on three levels.

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

Known cross allergies

Primary allergy on	Possible cross allergy / food allergy
birch	Pollen: hazel, alder, oak, red beech, ash, celery / mugwort, hornbeam Food: almonds, carrots, nuts (especially hazelnuts; walnuts; Brazil nuts), soy (milk) Fresh fruit such as pome and stone fruit: apples, pears, peaches, apricots, blackberries, strawberries, raspberries, plums / plums, cherries, mirabelle plums, nectarine, figs, jackfruit many different herbs and spices: parsley, pepper, paprika powder rare: tomatoes (raw), potatoes (raw), kiwi, lychee and avocado, celery
Grain pollen	Pollen: spelled, barley, oats, millet, corn, rice, wheat Grass pollen: ryegrass Food: cereal flour
Olive pollen	Pineapple, ascorbic acid, grasses, privet, horseradish
poplar	pasture
Grasses (pollen)	Pollen: stork grass, timothy grass, ball grass, ray grass (→ pineapple) Food: Potatoes (raw), soy + peanuts (legumes), peas, kiwis, tomatoes, melon, watermelon Grains: rye, oats, wheat, barley Peppermint, herbs / spices
mugwort	Pollen: sunflower family such as chrysanthemums / daisies, birch, dandelion, chamomile, sunflower, ragweed Food: Paprika, celery, carrot, potato, kiwi, cucumber, melon, artichoke, tomato, sunflower seeds, peanuts, lychee, mango, apple Spices: anise, coriander, chilli, dill, tarragon, fennel, ginger, chamomile, cardamom, garlic, caraway, nutmeg, paprika, pepper, peppermint, parsley, mustard, wormwood, lovage, cinnamon Herbs: basil, marjoram, oregano, thyme
celery	Pollen: birch, mugwort Food: carrot Spices: anise, basil, dill, fennel, oregano, cumin, coriander, lovage, marjoram, thyme
Ash	Pollen: olives, lilacs, privet, forsythia
Legumes	Peanut, bean, lentil, soybean, clover, alfalfa, lupine, liquorice, carob, gum arabic, tamarind, tragacanth
nuts	Hazelnut (→ rye flour), cashew, peanut (is not a nut, but a legume), almonds, poppy seeds, pistachios (→ sunflower seeds), sesame, walnuts, kiwi, strawberry (common nut fruit)
Ragweed (Ambrosia) increasing distribution in Europe	Chamomile, melon, banana
lilac	Ash / olive tree
House dust mites	Types of mites: storage mite Crustaceans: crabs, crabs, shrimp, scampi, prawns, lobsters, lobsters Other: red mosquito larva (in fish food), snails, mussels (e.g. oyster), cockroaches
Latex (in balloons, rubber gloves, diving suits, sticky sides of plasters, condoms, ...)	Pollen: mugwort, ragweed, timothy grass Food: bananas, avocados, papaya, kiwi, chestnuts, figs, raw potatoes, passion fruit, celery, tomatoes, peaches, buckwheat flour, paprika, mango, acerola Other: Weeping fig (ficus benjamina) (roasted chestnuts)
penicillin	Cephalosporins
kiwi	Pollen: mugwort, birch, grass Food: pineapple, apple, carrot, potato, rye flour, wheat flour Other: latex
fishes	Eels, perch, cod (→ surimi), carp, salmon, tuna, sole / sole, dentex, hen's eggs (through fish meal feeding)
Chicken egg	Duck, goose, chicken, turkey, seagull, parrot, canary, pigeon, budgie
Cow's milk	Beef hair, beef / veal, soy
Mold	Candida (→ Saccharomyces), Aspergillus, Alternaria, Cladosporium, Epicoccum, Fusarium, Penicillium
Gelatine (in gummy bears, yoghurt, ...)	Volume substitutes, plasma expanders (infusions!)
Hymenoptera (Hymenoptera)	Bee (→ bumblebee), wasp (→ hornet)

Differentiation from pseudo-allergies and intolerances

We do not speak of a cross allergy:

in the case of food intolerance or intolerance (these are often confused with a food allergy). This is where the reaction to biogenic amines such as histamines , serotonin and tyramine takes place
when other components of the diet, e.g. B. metals, cause an allergic reaction

Part of the diet	Contained in
histamine	Strawberries, tomatoes, anchovies, sauerkraut, tuna, red wine and sparkling wine
Serotonin	Pineapples, bananas and walnuts
Tyramine	Cheese, fish, yeast, sausage and chocolate
Salicylates	aspirin

Nutrition tips

Cross allergies can or do not have to occur. For example, around 70% of birch pollen allergy sufferers show when they consume various plant-based foods, such as B. apples, stone fruits, carrots, celery and products containing soy, at some point allergic reactions to these products.

Any diet should therefore be discussed in advance with a doctor in order to guarantee a healthy and balanced diet. In the case of more frequent complaints, keeping a combined complaint, nutrition and pollen diary can help to identify possible food allergies, which can then be circled further with the help of an elimination diet . Often it is then sufficient to heat-treat the food (e.g. microwave), to switch to other types or to refrain from consuming it during the pollen season.

literature

Food allergies due to immunological cross-reactions (PDF; 311 kB) Guideline of the food allergy working group of the German Society for Allergology and Clinical Immunology (DGAI) and the Medical Association of German Allergologists (ÄDA). In: Allergo J , 2005, 14, pp. 48-59

Web links

Cross allergy German Allergy and Asthma Association

Individual evidence

↑ ^a ^b Vieths, S .: Current understanding of cross-reactivity of food allergens and pollen . In: Ann NY Acad Sci. . 964, 2009, pp. 47-68. PMID 12023194 .

[Vieths-1] Vieths, S .: Current understanding of cross-reactivity of food allergens and pollen . In: Ann NY Acad Sci. . 964, 2009, pp. 47-68. PMID 12023194 .