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Cross-allergy means that in a person allergic to one allergen (e.g. birch pollen), unwanted symptoms may also appear after contact with another allergen (e.g. apple). What exactly is cross allergy? What are its symptoms? What is diagnosis and treatment? Which allergens cross-react? These and other questions are answered by an expert - Zygmunt Nowacki, MD, PhD, specialist in children's diseases, allergologist and lecturer at the Polish Society for Combating Allergic Diseases.

Cross-allergyis that in a person who is already allergic to one allergen, an adverse reaction may also appear after contact with another allergen. All because of the structural similarities in the chemical structure of inhalation, contact and food allergens.

Cross allergy - what is it?

It is known that the proteins present in plant pollen are sometimes identical or very similar in terms of chemical structure to some food allergens.

Therefore, IgE antibodies produced by the immune system in response to contact with the allergen may not recognize differences in the structure of individual antigens and treat them as the same.

"By mistaking", they attack all similar proteins, which results in the coexistence of allergy symptoms in people who are simultaneously hypersensitive to food, inhalation and contact allergens (panallergens).

As much as 30 percent people with inhalation allergy are also allergic to certain foods.

This is how cross-allergy is defined in medicine. Classic allergic cross-reactions occur mainly between pollen and certain fruits and vegetables (e.g. birch-apple-carrot; mugwort-watermelon-celery) and usually concern patients with symptoms of allergic rhinitis and bronchial asthma.

American scientists have discovered a new type of cross allergy to red meat and ticks. It can develop up to 5 percent. people bitten by this arachnid.

Cross-allergy symptoms can also trigger:

  • unrelated plant species (e.g. beech-birch-hazel-hornbeam)
  • latex and fruit (banana, kiwi, avocado, chestnut)
  • house dust mite and seafood (crab, shrimp, oyster)
  • pork and cat hair
  • milk from cows and other mammals(e.g. goats, sheep)
  • chicken and other eggs, e.g. quail, duck, turkey, guinea fowl or even ostriches

Cross-allergy - when do allergic cross-reactions arise?

- The phenomenon of cross-allergy is conditioned by the structure of the so-called main antigens, recognized by the human immune system and stimulating the synthesis of specific asIgE antibodies, explains Dr. Zygmunt Nowacki, MD, specialist in children's diseases, allergist and lecturer at the Polish Society for Combating Allergic Diseases.

Cross-reaction is highly probable when the homology (i.e. similarity) of the protein sequences in the structure of the so-called major antigens reaches 70 percent. With values ​​not exceeding 50 percent. cross-reactions are very rare.

In 1976, it was discovered that profilins, or proteins widely distributed in the plant kingdom (similarity of 70-80%), are "the bridge between food and inhalation allergies."

They are responsible for allergic cross-reactions on the line: birch / mugwort-celery-spices or grass-celery-carrot pollen. Similarly, cross-reactions of latex with banana, pineapple, celery or paprika are explained by the presence of profilin in them. When explaining what cross-allergy is, lipid-transfer proteins should also be mentioned.

They hide behind cross-reactions between unrelated vegetables and fruits (e.g. peach, plums, apples, cherries, corn, broccoli, parsley) and between them and barley, wheat, soybeans and nuts. In this case, sensitization may occur orally, not necessarily related to pollen allergy.

Worth knowing

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Table of the most common cross-reacting allergens

Birchbeech, oak, alder, ash, hazel, chestnut, olive tree, poplar, grasses / cereals, mugwort, chamomile, stone fruit (apple, pear, plum, peach), banana, kiwi, lychee, mango, orange, carrot (raw), potato (raw), celery, soybeans, tomato (raw), anise, curry, pepper, pepper, cumin, coriander, nuts, latex
Bylicabirch, olive tree, grass / grain, ambrosia, chamomile, pyrethrum (daisy), sunflower, stone fruit (apple, pear, plum, peach), kiwi, mango, peas, carrot (raw), celery, tomato (raw), anise, curry, dill, pepper, pepper, cumin, coriander, peanut and other nuts, latex
Latexbirch, grasses / cereals, mugwort, ambrosia, stone fruit (plum, peach), banana, kiwi, mango, melon, papaya, avocado, potato (raw), celery, tomato (raw), peanut, horse chestnut, ficus
Celerybirch, grasses / cereals, mugwort, ambrosia, stone fruit (apple, pear), mango, melon, cucumber, carrot (raw), tomato (raw), dill, pepper, pepper, cumin, coriander, latex
Grasses / grainsbirch, ash, olive tree, rape, mugwort, sunflower, stone fruit (apple, pear, plum, peach), kiwi, melon, celery, tomato (raw), onion, flour (rye, wheat, oats ), rice, latex

Cross allergy - symptoms

Taking into account the disease entity, which is cross-allergy, the clinical symptoms of this disease can be extremely diverse, but most often it is manifested by disorders of the respiratory system:

  • rhinitis
  • cough
  • shortness of breath

and digestive system:

  • stomach pains
  • diarrhea
  • nausea
  • vomiting

If the symptoms concern people with simultaneous inhalation and food allergy, they usually manifest themselves 15-30 minutes after consuming fresh fruit and vegetables.

In people allergic to pollen, the so-called oral allergy syndrome (OAS). His symptoms are:

  • itching
  • baking
  • tingling in throat
  • swelling of the lips and / or palate and / or tongue

- Allergic cross-reactions can also trigger skin symptoms, such as hives, erythema or exacerbation of changes in the course of atopic dermatitis. On the other hand, patients who suffer from bronchial asthma at the same time are at risk of acute systemic, life-threatening symptoms - allergist says.

Cross allergy - diet. What not to mix with each other?

Cross allergy - what to eat?

- Cross-allergic people can eat cooked or baked fruits / vegetables, and must beware of raw ones. However, in the case of allergens such as milk or wheat, thermal treatment is not enough. This is because allergens can possess bothepitopes (fragments of the allergen that connect to antibodies) linear - resistant to high temperature - as well as conformational epitopes, sensitive to it - explains an allergist specialist.

Cross allergen table - grains, meat and eggs

allergencross-reacting allergens
peanutmugwort, stone fruit (plum, peach), peas, soybeans, tomato (raw), latex
nuts (other)birch, hazel, mugwort, stone fruit (plum, peach) kiwi, flour (rye, wheat, oats), sesame, poppy seeds
flour (rye, wheat, oats)grasses / grains, kiwi, nuts, rice, sesame, poppy seeds
ricegrasses / grains, flour (rye, wheat, oats)
sesamekiwi, nuts, flours (rye, wheat, oats)
makkiwi, nuts, flours (rye, wheat, oats)
crustaceanshouse dust mite
pork meatcat hair
chicken egglatex
peamugwort, peanut

Cross allergy - diagnosis. What tests should be performed?

Despite the advances in medical knowledge, doctors still cannot say with certainty whether a given patient will develop cross-allergy. It is only possible to determine the probability of such a reaction.

In the case of oral allergy syndrome, the key to diagnosing this disease is the link between allergy to airborne allergens and allergy to food components responsible for the symptoms.

People allergic to latex may also be allergic to:

  • birch
  • bylicę
  • grass / grain
  • ambrosia
  • stone fruit (plum, peach)
  • bananas
  • kiwi
  • mango
  • melons
  • papaję
  • avocado
  • potatoes (raw)
  • celery
  • tomato (raw)
  • peanuts
  • chestnuts

- In the case of other syndromes, diagnostic problems are largely due to the variety of consumed foods, the dominance of already processed foods (which significantly affects the variability of the sensitizing power), as well as the storage conditions of food and added preservatives and thickeners, acidifiers, as well as stabilizers, emulsifiers and antioxidants - explains Dr. Nowacki.

The diagnosis of the disease is made even more difficult by the fact that it is used in medicinethere is no sufficiently reliable test with the required specificity and sensitivity to unambiguously indicate and / or predict such a reaction.

Hence, the diagnosis of classical cross-reaction is based on a study with the use of recombinant allergens and new diagnostic techniques, such as, for example, ImmunoCAP ISAC (Immuno Solid-Phase AlleroChip).

- Although this method is a precise diagnostic guideline, unfortunately it entails a high cost of the test, which is a significant limitation - the doctor emphasizes.

Cross allergen table - pollen

allergencross-reacting allergens
beechbirch, alder, hazel
alderbirch, beech, hazel
ashbirch, lilac, olive tree, grass / cereal, ambrosia
withoutash, olive tree
hazelbirch, beech, oak, alder, nuts
rapebirch, grasses / grains
ambrosiaash, mugwort, chamomile, stone fruit (apples, pears) melon, celery, latex
chamomile (also in tea and medicines)grasses / grains, birch, mugwort, ambrosia
chrysanthemum (margaret)bylica, sunflower
sunflower (also grains)olive tree, grass / cereal, mugwort, chrysanthemum
olive treebirch, ash, lilac, mugwort grass / cereals, sunflower

Cross allergy - treatment

A key component of cross-allergy therapy is, of course, to avoid the causative agent of the disease (if specified). An example of such a procedure is, for example, an elimination diet. However, do not use it "just in case", but exclude possible food products after noticing symptoms of the disease immediately after eating them.

Your doctor may also recommend taking antihistamines that block the activity of histamine - a substance that mediates the course of an allergic reaction.

It is worth remembering that the newest drugs in this group (i.e. the second generation - e.g. fexofenadine, desloratadine or one of the most modern substances - bilastine, combating the symptoms of allergic rhinitis, allergic conjunctivitis and skin symptoms such as urticaria) oral application lasting up to 26 hours) have no cardiotoxic effect anddo not disturb psychomotor functions.

The first generation antihistamines (e.g. antazoline, clemastine, promethazine) have such an effect. These drugs - depending on the doctor's recommendations - should be taken constantly or temporarily in the event of symptoms.

In the event of exacerbation of symptoms, the doctor may decide to use steroid therapy. Glucocorticosteroids in allergy can be administered orally or intravenously. Due to the fact that their use is associated with quite numerous side effects, inhaled glucocorticosteroids have also been introduced into treatment - administered directly into the bronchi or, for example, intranasally, in doses thousands of times lower than the oral ones. As a result, the side effects are not felt like that by the patient.

One method of treating cross-allergy is also specific immunotherapy. It consists in the regular intake of allergens (initially allergenic - e.g. birch pollen) in a minimum dose, which does not cause allergy symptoms, but gradually immunizes the body to its effects. This allows you to give up the constant application of drugs and finally breathe a sigh of relief.

Cross-allergen table - vegetables and fruits

allergencross-reacting allergens
stone fruit (apple, pear)birch, grasses / cereals, mugwort, ambrosia, stone fruit (plum, peach), potato (raw), celery, tomato (raw)
stone fruit (plum, peach)birch, grasses / cereals, mugwort, stone fruit latex (apple, pear), peanut (peanut) and other nuts
bananabirch, kiwi, melon, avocado, latex
kiwibirch, grasses / cereals, mugwort, banana, avocado, nuts, flour, sesame, poppy, latex
mangobirch, mugwort, carrot (raw), celery
melongrasses / grains, ambrosia, banana, cucumber, carrot (raw), celery, latex
avocadobanana, kiwi, latex
cucumbermelon, carrot (raw), celery
carrot (raw)birch, mugwort, mango, melon, cucumber, celery
potato (raw)birch, stone fruit (apple, pear), tomato (raw), latex
tomato (raw)birch, grasses / cereals, mugwort, stone fruit (apple, pear), potato (raw), celery, peanut, latex
oniongrasses / grains
pepperbirch, mugwort, celery

Read also:

  • Allergy - symptoms, types, treatment
  • Inhaled allergy: causes, symptoms and treatments
  • Food allergy: causes. List of products that cause food allergies
  • Contact allergy in children: causes, symptoms, treatment
  • Skin allergy: how to fight allergy
  • Allergy or cold? How to distinguish a cold from an allergy?

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