Allergens

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• Allergens in the Environment

An allergen is an exogenous antigen that is able to elicit a pathological (allergic) immune response in a susceptible individual.

Types of allergens

We divide allergens into several groups.

Pollen

Pollen is one of the most important allergens. The exacerbation of allergies related to pollen are linked to the flowering period of plants containing pollen. Pollen is transferred through the air and thus, it is very beneficial for allergy sufferers to follow pollen news.

• Sometimes the disease lasts all year round, usually during the period of the highest occurrence of the allergen (in summer) the symptoms exacerbate.
  • Pollen of grasses, grains, herbs, shrubs, trees has been causing problems since February,
  • flower pollens usually do not cause allergies (except dandelions).

10-20 pollen grains in 1 m³ of air already cause problems (eg between mid-May and July there are 100-500 grains per 1 m3 of air). The worst is warm weather, windy; rain reduces the risk of trouble.

• Significant cross-reactivity has been observed in grasses and birch trees - the pollens of these trees can cross-react with allergens of some fruits and vegetables.

The most common manifestations:

• allergic rhinitis;
• conjunctivitis;
• bronchial asthma;
• in some patients, skin manifestations (urticaria) also occur after contact with the allergen.

Dust

Dust is a ubiquitous agent of various compositions:

• waste particles of objects and substances;
• animal, human epithelium;
• hair and hair;
• microorganisms or body remnants of microorganisms, excrement, insects, mites;
• in house dust and mold Alternaria, Cladosporium, Aspergillus, Penicillium, Mucor, Rhizopus.

Arthropods

Various components of insects (poisons, saliva, peeled cuticle, excrement) can cause allergies. Allergies are caused by pinching, sting, skin contact, inhalation. Dead insects are also a source of allergens.

Mites

Mites are a common component of house dust. The basic condition for their reproduction is humidity (optimum 70–80% at 25 ° C). They most often multiply in mattresses, most of them are in bed linen, upholstered furniture, carpets and curtains. Mites most often feed on mold. It is determined by counting under a microscope, by ELISA, by quantification of guanine (in mite excrement).

Bees and wasps

• Bees and wasps are among the bee insects.
• The bee venom contains phospholipase A2, hyaluronidase, acid phosphatase and melitin.

Melitin:

• makes up 50% of the sting content;
• lyses erythrocytes;
• affects myocardial activity and blood circulation;
• has a curarizing effect.

There are 4 allergenic fractions in wasp, wasp and hornet venom: phospholipase A, phospholipase B, hyaluronidase and antigen 5. There is a different cross-reactivity between antigens, which is weak between bee and wasp venom, but strong between wasp and wasp venom. Insect poisons contain toxic components that trigger an anaphylactoid reaction and can cause anaphylactic shock.

Domestic and farm animals

Allergens from pets and livestock cause allergies in 5% of people. The most common are allergies to dogs and cats, but also to rabbits, horses, hamsters and exotic birds. Scales, skin and fur are allergically important, but the feces, urine or saliva of animals can also be allergicized. The high incidence of allergens is especially in the saliva of cats. By licking them, it gets on the fur and into the environment.

Cat allergens:

• Fel d I antigen;
• feline serum albumin;
• epithelial allergens.

Dog allergens:

• epithelium;
• power;
• serum albumin.

Horse allergens:

• serum albumin;
• allergens in the skin, fur.

Exotic birds:

• mites in feathers.

Fungi and other microorganisms

Molds occur in damp rooms (under tiles, wallpaper, in the air), in buildings without permanent occupancy and with insufficient ventilation. If the patient describes the problem, for example, only in the cottage, there is a suspicion that the cause may be mold. Problems can sometimes be seasonal in nature. Rain and fog increase the amount of mold in the air.

Alternaria:

• ubiquitous;
• saprophytically occurs on plants, food;
• most in autumn, spring;
• main allergen Alt and I.

Aspergillus:

• stored grain, vegetables, fruits, compost, flour;
• skin;
• evokes reactions I., III. and IV. type.

Penicillium:

• ubiquitous, year-round;
• higher humidity is important for growth.

Another source of allergies are microorganisms living in air conditioners: Actinomyces, protozoa, fungi that cause so-called air conditioning disease.

• Farm lungs: professional damage; a form of exogenous allergic alveolitis; the cause is thermophilic actinomycetes.
• Algae (after bathing in the pond).

Foodstuffs

Foods cause allergies, which are often diagnostically problematic and depend on the preparation of the food (there is traces of ATB in the meat, pesticides in the plants).

• Most often allergies to eggs, fish, hazelnuts, milk, celery, fruits, vegetables, flour, peanuts, meat, potatoes, cocoa.
• Allergens are mostly the nature of the glycoprotein (molecular weight 10,000-40,000); different physical properties.

Cow milk

Cow's milk contains casein, β-lactoglobulin, serum albumin, α-lactalbumin, which are thermostable allergens. Milk allergy is rare in adults, more common in children (specific IgE until adulthood). Hypoallergenic milk is also currently produced: most proteins have a molecular weight of less than 3,400, so they do not cause sensitization.

Eggs

The white allergens most often, the allergic reaction is directed against the following proteins: ovalbumin (the main thermolabile allergen), conalbumin, ovomucoid (the main thermostable allergen), ovoglobulin, ovomucin.

There is liver in the yolk, which also often causes an allergic reaction. Cross-reactivity with protein and feather allergens, eggs and poultry is quite common.

Fish

Fish sarcoplasm components resist cooking and cause allergies. Other allergens are histaminoliberators, histamine in tuna. They cause asthma and anaphylactic shock.

Meat

The most allergenic is pork, whose allergens resist cooking. People who are highly sensitive to penicillin may react to meat and people who are hypersensitive to eggs may react to poultry meat.

Cereals

Cereal allergens are mainly albumins and globulins in flour. We often encounter a cross-reaction of peanut cereals. Gliadin causes celiac sprue; It is rich in glutamic acid, proline and disulfide bonds. Some antigens are found in spirits made from the respective grains. Some medicines also contain gluten, corn starches and grains.

Vegetables and fruit

Common causes of allergic reactions:

• peanuts, soy, peas, beans;
• cruciferous vegetables: horseradish, mustard, radish, cabbage; acyl isothiocyanates; masked allergens;
• carrots: celery; anaphylactic shocks common; preparation of celery and carrots can cause hives on the hands, runny nose, tearing;
• eggplant vegetables: tomato X pepper, eggplant, potatoes, grass pollen; hives, eczema, aphthae;
• fruit: apple, hazelnut; cross-allergy with tree pollen; peach; Quincke's edema of the lips, tongue, itching, runny nose, conjunctivitis; strawberry causes urticaria in children;
• cocoa and chocolate: anaphylactic reaction exceptional; often urticaria, headache, dermatitis; you need to consume large amounts of chocolate.

Food additives

• Dyes: azot; skin and respiratory manifestations, may cause anaphylactic shock.
• Preservatives: sulphites; for the preservation of dried fruit, in must, wine, beer, vinegar, in medicines (corticoids); bronchospasm; benzoic acid, quinine, biphenyls.
• Allergies to gelatin, sodium glutamate, aspartame, papain; α-amylase causes asthma in bakers.
• Contaminants in food: pesticides, insecticides, fungicides; artificial cattle nutrition; nickel (after preparation in nickel-plated dishes).
• Hypersensitivity to yeasts and fungi → allergies to beer, blue cheese, jams.

Allergy treatment

See the "Allergy Treatment" page

Links

Related articles

• Allergy
• Allergy treatment
• Important allergens
• ACD (signpost)

External links

• Additives
• [1] (pollen calendar - pollen service)

References

• HOŘEJŠÍ, Václav a Jiřina BARTŮŇKOVÁ. Basics of immunology. 3rd edition. Praha : Triton, 2008. 280 s. ISBN 80-7254-686-4.

Category: Immunology Category: Hygiene Category: Microbiology