An allergy sufferer often knows which irritant causes abnormal reactions in his body. At the same time, he may unexpectedly develop an allergy to other substances, which at the molecular level turn out to be “doubles” of the main allergen. Let's get acquainted with the concept of “cross allergy”; a table with possible types of allergens will help with this.
Cross allergy calculator
A good way to determine which foods may cause cross-allergy is to use a table. However, there is an alternative, more convenient option - a “calculator” or filter.
In order to find out which allergens can cause cross-reactions, you need to:
- select already known stimuli from the list;
- Having noted them all (for example, you are allergic to wheat and honey), you need to click on the “Show result” button.
The necessary information will appear on the updated page.
However, a “naked” answer is not always enough. To fully control the situation, you must have some knowledge about the phenomenon of cross-reactivity.
- Food products
The immune system is a very finely organized structure. All its elements are characterized by high specificity: one protein is “matched” by a completely specific other. Each antigen stimulates the formation of specific antibodies that have no effect on any other proteins.
However, as with any system, there is a possibility of error, or at least exceptions to the rules.
Thus, if two different proteins have several similar elements (epitopes - areas that determine immunoreactivity), some of the antibodies formed in response to the appearance of the first substance may also react to the second. This phenomenon is called cross-reactivity and plays a large role in the development of allergic reactions.
How and when birch trees bloom
The process of birch flowering itself begins with sap flow - sap begins to drip from the trees. After 15-17 days, the buds swell, which soon bloom into the first leaves. At this moment, the 20-day flowering begins. From late July to early August, fruits appear on the trees - small winged nuts called lionfish.
Only male catkins bloom in birch trees. Female earrings are difficult to see in the spring; they look like sticks and only after pollination become like an earring.
Allergy sufferers have a sign: if February is cold, then the dusting will be explosive (since the earrings undergo stratification and gain strength). If February is warm, there will be no violent dusting process.
Warm winters without snow also affect pollen. Earrings form in the fall and require cold to develop properly.
Birch blooms differently in different regions. In St. Petersburg this is only a month, but there are regions where birch is dusty from April to September.
In the south of Russia, birch trees bloom in March, in the central regions in mid-April, and in the north of the country in May.
Experienced allergy sufferers claim that birch always strictly adheres to its schedule: it begins to dust, regardless of the weather, at approximately the same time. However, wet weather can prolong flowering time, while dry weather shortens it.
After a light rain, the pollen becomes more aggressive. For pollen grains, air humidity is a signal for reproduction. Pollen releases allergen proteins into the atmosphere, which are smaller than pollen grains and more easily penetrate the bronchi.
During a thunderstorm, the same thing happens - the amount of allergen proteins in the atmosphere increases sharply. Thunderstorm asthma is a dangerous condition that often leads to bronchospasm.
At such times, it is better to refrain from walking and go outside after a good, long, multi-day downpour.
The dusting comes to an end when the catkins darken and fall off, and yellow dust disappears from cars and sidewalks.
Stages of birch dusting:
Silver birch begins to bloom first in St. Petersburg and Moscow, followed by white or downy birch (Betula pubescens).
In Moscow, birch flowering begins in the last days of April and ends by the first days of July.
In St. Petersburg, the dust schedule is slightly behind the Moscow one. But the peak of flowering usually coincides in both capitals and falls on the May holidays: May 9-10.
Pollen appears first in cities, and then, with an approximately week delay, in regions. Birch flowering calendar in Russia:
| March | April | May | June | July | August |
| Northwest | |||||
| Middle lane | |||||
| Volga region | |||||
| Ural | |||||
| Siberia | |||||
| Crimea |
Classification of allergens
It would seem, why should the average person delve into allergology and know what types of allergens exist? However, this information is useful: based on it, you can predict which products may develop a cross-reaction and which will not.
There are quite a few classifications of allergens. The most common division is into endogenous and exogenous. In the first case, a reaction develops to some tissues of one’s own body when the integrity of biological barriers is violated (for example, when the eye or testicle is damaged) and this section is of little interest to us.
Example of some birch cross allergens
Exogenous allergens include “third-party” proteins, which can be:
Infectious:
- bacterial;
- viral;
- fungal;
- parasitic;
Non-infectious:
- pollen;
- food;
- household;
- epidermal;
- insects;
- medicinal;
- professional.
In most cases, cross-reaction occurs between pollen and food allergens, both within each group and between species, but allergens of any type can be involved.
There are three interaction options:
- With distinct clinical symptoms. This includes hypersensitivity to different products of the same class (for example, to several types of fish, to shrimp and squid, to oranges and lemons, etc.), “bird-egg” reactions (if there is hypersensitivity to chicken eggs, undesirable symptoms appear upon contact with feather pillows), as well as fruit-birch syndrome (cross-allergy to birch pollen and some fruits);
- With not always obvious symptoms. This group usually includes cross-reactions between proteins of tree and grass pollen and fruits containing cysteine (kiwi, papaya) and house dust mites, latex-fruit syndrome.
- With no clinical manifestations. In this case, only an immunoglobulin test can detect the presence of cross-reactions.
The main criterion by which one can determine whether a cross-reaction will develop is the presence of identical pathogenetic proteins in two allergens. These are small protein molecules that are formed in plants as a result of exposure to unfavorable conditions - infectious diseases, ultraviolet radiation, damage to the integrity of structures, chemicals, etc.
In different parts of plants, the level of content of these proteins differs, which determines the unequal strength of influence on immunity.
There are 14 groups of proteins, different in the set of amino acids and, accordingly, in biological and enzymatic activity. Only six play a significant role:
| Protein | Description | Where is it contained? | Disease |
| PB-2, beta-glucanase | A hydrolysis enzyme that destroys the wall of mold fungi. | Latex, bananas, kiwi, figs, tomatoes and potatoes | Fruit-latex syndrome |
| PB-3, endochitinase | Breaks down the exoskeleton of insects and the cell wall of fungi | Latex, avocado, banana, chestnut | Fruit-latex syndrome |
| PB-4, chitinase | Breaks down chitin, protects against damage | Latex, turnip, potato | – |
| PB-5, thaumatin-like protein | Provides antifungal protection, protection from frost and drought | Cherries, apples, peppercorns, mountain cedar | – |
| PB-10, ribonuclease | The basis of cross-allergy, the main allergen of birch | Birch, hazel, alder, chestnut, apple, celery, cherries, peaches, apricots, pears, carrots, tomatoes, parsley, wormwood, etc. | Fruit-birch syndrome, birch-wormwood-fruit-vegetable syndrome |
| PB-14, lipid transfer protein (LTP) | Transfers phospholipids from liposomes to mitochondria, has antimicrobial and antifungal activity | Peaches, apples, soybeans, apricots, plums, cherries, barley, latex, chestnuts, hazelnuts, walnuts, wormwood, ragweed, asparagus, grapes, corn, olive |
In addition to pathogenic proteins, there are several other factors that cause cross-reactions:
- storage proteins (important for cereals and legumes);
- 2S albumins (mustard, rapeseed, beans, nuts, including peanuts);
- thiol proteases (found in papaya, kiwi, pineapple, soy);
- protease inhibitors (tomatoes, potatoes, beans, cereals).
It is better to know the enemy by sight, or a birch under a microscope
Birch belongs to the Beechaceae family, which is divided into subclasses: birch, hazel, beech, elm, casuarinaceae, myricaceae, roiptelaceae, nutraceae and others.
Birch is unpretentious and tenacious - a kind of weed among trees.
Birch trees also have advantages: they are beautiful and perfectly clean the air from unpleasant odors and pollution, which is why they are often planted next to busy highways.
In Moscow and St. Petersburg, the most generous species of birch (Betula pendula) are the most generous with pollen. This type of birch occupies large areas in Europe, Asia and even North Africa.
Birch trees that grow all over the world:
Scientists count about 65 species of birch trees.
- Birch “Cherry”. Habitat: Baltic states, Russia, Belarus.
- Birch “Black” or Daurian. This species can be found in Siberia, Mongolia, the Far East, China, Japan, and Korea.
- Birch “Paper”. It got its name due to the fact that its bark was used as paper. Grows in Western Europe. In Russia it is found in parks, botanical gardens and forest stations.
- Birch Yellow or American. Found in Asia and North America. Blooms from late spring to mid-summer.
- Birch “Small-leaved”. Grows in Siberia and Mongolia.
- Birch “Ribbed” or Far Eastern. Korea, China, Russian Far East.
- Birch “Woolly”. Low species, from 3 to 25 meters. Grows in Yakutia, Khabarovsk Territory, Irkutsk Region, Primorsky Territory.
- Birch “Schmidt” or Iron. They live up to 350 years. They grow in Japan, China, and the south of the Primorsky Territory of Russia. This type of birch is especially pollen-bearing.
The bark of most birch species contains a resinous substance - betulin. Betulin gives the tree a white color and protects it from severe frosts and fungus. The most betulin is found in the bark of downy birch.
Watch a video about the beneficial properties of birch. Allergy sufferers should not take it to heart
