The allergy in 5 questions

The allergy in 5 questions

Is the allergy a hereditary disease? Can one become allergic to pollens at any age? Why there are more and more people allergic to pollens in the cities? Which is the role of the weather? Dr. Patrick Rufin*, allergist and lung specialist, bring precise answers to all these questions.

Is the allergy a hereditary disease?

Dr. Patrick Rufin: The allergic demonstration is the point of meeting between a ground genetically predisposed on the hereditary plan and the environment. When one speaks about environment, it is in the broad sense term, i.e. the environment inside the habitat, outside, the pneumallergenes (allergens being in the air) and the allergens food.
There is thus indeed a hereditary factor, but this one is not constant and more constitutes the point of meeting between two mechanisms.

Can one become allergic to pollens at any age?

Dr. Patrick Rufin: So that a person presents symptoms, like those of the hay cold, it is necessary that the organization sensitized itself. There exists one period during which an immune reaction will be set up, without there being clinical demonstration.
In other words, the symptoms appear only at the end of one certain time, when the degree of sensitizing is sufficient.
However, in the young child, sensitizing is faster and thus the symptoms more quickly appear, in particular for the allergies to the acarina that with pollens.
Thus, in the child, the demonstrations of the hay cold type generally appear towards the age of 7-10 years. They can appear earlier but it is rare.
On the other hand, in the adult, these demonstrations can appear overall at any age, knowing that last around fifty, it is rare to even appear for the first time a true hay cold.
It will be retained that the great periods of appearance of the symptoms of the pollinose are towards 7-8 years then in the young adult.
But because of the climatic disordered states, the period of pollination changed and the time of pollination became longer, which supports the earlier appearance of the symptoms of allergy to pollens.

Can an allergy involve another of them?

Dr. Patrick Rufin: From the moment when one can become allergic, one can sensitize oneself with several allergens and in particular with pollens, they is what is called the allergies crossed between various pollens. Why? Because there exist families of pollens, species of trees or plants, which have joint antigens, with the result that one sensitizes oneself easily with several of them.
For example, the people sensitized with pollens of birches, a major allergen in the northern area of France, it with other pollens of trees of the same family, are very often also bétulacées (hazel tree, alder, charm). As for the people sensitized with pollens of graminaceous, they are often sensitized with several pollens: dactyl, fescue, ivraire, phleum…
The allergic subjects thus are often polysensibilisés in term of plants of the same family.

In addition, as from the moment when one is sensitized with pollens, i.e. the organization is able to manufacture antibodies of the allergic type, if an animal at the residence, there arrives are great chances that one sensitizes oneself with this new allergen at the end of a certain time.
This phenomenon also depends on the place of life. Let us take the example of a person living in the north of France and whose organization is sensitized with the pollen of birches. If it leaves food in midday, there is strong chance that she sensitizes herself with the cypress at the end of 2-3 years.
When she lived in north, not being in contact with pollens of cypress, she could not be allergic to the cypress, but becomes it while changing area of residence.

Which is the weather most favorable to pollens?

Dr. Patrick Rufin: Pollens allergisants, are known as anémophiles, i.e. they are transported by the wind.
There exist two types of pollens: the entomophilous pollens, transported by the insects and which are slightly allergisants because of big size and thus little transported by the wind until in the higher respiratory tracts, and pollens anémophiles which are more allergisants, because of small size, practically invisible and thus easily transported by the wind.
What wants to say that one is exposed more to pollens if the weather is hot (period of pollination), if there is wind, and in addition if it reigns a certain percentage of moisture in the air because grains of pollen tend to explode. Let us recall that the grain of pollen is a kind of hull which contains a small ball very allergisante.
These conditions all are met right before a storm (heat, wind and moisture). Thus the people allergic to pollens very often feel symptoms per thundery weather. Of course, if it rains much, the rain washes the air and then makes disappear pollens and the symptoms with.

Why there are more people allergic to pollens than formerly and in particular in the cities?

Dr. Patrick Rufin: This phenomenon is explained by a synergy between various mechanisms.
Firstly, the various pollutants that we breathe all the day cause a local ignition of our respiratory mucous membrane, which makes it more sensitive to the allergens.
Secondly, the chemicals at the origin of pollution deteriorate the grains of pollens, which then release more easily their allergens. Thus a person usually answering 1000 grains of pollens, will answer only 500 grains if those passed in a polluted air.
Thirdly, the plants which push in a polluted air pollinate more to be defended and thus manufacture more pollens.
These three mechanisms are enough to explain why there are more and more people allergic to pollens in urban area. And of course, these people sensitized in urban area will develop even more symptoms if they go to the countryside…