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Why Is Ambrosia So Dangerous?


Among the plants that emit allergenic pollen, ragweed is more and more confidently occupies the first line. Even in Ukraine. Having been brought here a hundred years ago along with grain from the United States as part of the food aid that America provided to the USSR, ragweed has already spread throughout the country. Mostly we are talking about ragweed Ambrosia artemisiifolia In the southern and southeastern regions, allergy to it takes the leading place among all types of sensitivity. So why is ambrosia so dangerous?     

In fact, this question has several answers. One of them is the allergenicity of the ragweed proteins themselves, the other is the structure of the pollen grain. Climate change processes are also important. They affect the main allergen of ragweed pollen. Don’t believe me? Let’s figure it out together. 

So, until now, 8 allergenic proteins have been discovered and described in ragweed pollen. According to other sources, there may be more than 40 of them. The main place among them is occupied by Amb a 1 – the main or major allergen of ragweed. It belongs to the class of pectate lyases The concentration of this enzyme increases as the pollen matures. After all, it is this protein that is responsible for the formation of the growth tube. It is formed when the pollen – the plant sperm – reaches the stigma of the flower pistil and must now reach the egg through the pistil. And pectate lyase helps her in this. That is why the concentrations of this allergenic protein are high in ragweed pollen, which ripens closer to autumn. He has time to form in this pollen. Therefore, as doctors note, the reactions of sensitive people to ragweed pollen are more pronounced in September. At the same time, there is a second wave of ragweed blooming in Ukraine.   

By pectate lyase sensitive more than 95% of patients with symptoms of allergy to ragweed. In addition to its function, the allergenicity of this protein can also be due to its structure – our immune system perceives it as an enemy agent, as well as the combination of Amb a 1 with other pollen substances. For example, the flavonoids that contribute to the yellow color of pollen can also trigger an immune response. These substances can combine with Amb a 1 and provide the plant with a protective effect. And proteins that other organisms use for defense are often perceived by our immune system as hostile. Flavonoids, on the other hand, are known for their ability to modulate the immune response by enhancing the response to pollen allergens. 

Other proven allergens include ragweed – and Amb a 4 – a defensin-like protein that also has protective properties. Amb a 6 is a lipid transfer protein or LTP. It is known for its persistence as well as its ability to cause severe allergic reactions. Amb a 8 is a profile This protein poses little threat. However, hypersensitivity to it can also mean an allergy to a wide range of herbal products and latex. After all, profilins are proteins that are found in almost every plant. Amb a 9 and Amb a 10 are polcalcines They may be responsible for cross-reactions with grass allergens in people who are sensitive to this ragweed protein. It is cereals that are known for the presence of polcalcines . Amb a 11 is a cysteine ​​protease. Protein responsible for the plant’s response to stress. Its amount decreases with the maturation of the plant. However, two-thirds of people who are allergic to ragweed pollen react to it. And the last protein – Amb a 12 – enolase This protein is key for the growth and development of plants and, as a rule, there is a lot of it in cells. Two-thirds of people who are allergic to ragweed also respond to it.       


But a wide range of resistant proteins-allergens are not all the reasons for the allergenicity of this plant’s pollen. The structure of the pollen grain also contributes to this property. It has a size of about 20 micrometers in ragweed. This pollen size is inherent in most allergenic plants. Their pollen is not too small, but also not very large. In addition, in ragweed, its surface is abundantly covered with thorns. It is they who help the pollen stay on the surface of the nasal mucosa. Therefore, the pollen has time to swell, burst, and the allergenic cocktail gets from it onto our mucous membrane, from where it is absorbed into the blood.


Also, ragweed is almost the only plant for which the role of global warming has been confirmed for the allergenicity of pollen. In particular, there are many works by Western scientists showing that with an increase in temperature and CO2 concentration in the air, the concentration of proteins in ragweed pollen also increases In particular, the same Amb a 1. 

Thus, the combination of all these factors, as well as the widespread distribution of this plant in abandoned areas, which are often not checked by humans, contributes to the fact that ragweed pollen concentrations in the season are much higher than the clinically significant threshold of 10 pollen grains per cubic meter of air. And this pollen, due to its large amount, can be in the atmosphere both day and night. And it is very difficult for sensitive people to avoid contact with her.

And, therefore, so that people sensitized to ragweed pollen do not develop symptoms of hay fever, in advance, before the start of the season, they are recommended to undergo a course of allergenic immunotherapy (AIT). It is she who is the only way to treat ragweed allergy.

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