Undoubtedly, allergies often cause asthma. The terms asthma and allergy are often used as synonyms by laymen and in medical terminology. Unfortunately, only a few cases of asthma are really caused by allergies.
The term allergy is difficult to define. Allergy basically means "to react differently". As a matter of fact, many asthmatic patients react differently to various kinds of inhaled substances than do healthy people. Antibodies, which are usually significant in the protection from pathogenic agents, initiate a fateful chain of reactions in the case of asthma.
Allergic asthma due to pollen is a good example. Whereas about 90 percent of the population can inhale large amounts of pollen from grasses and ragweed, which bloom during spring and autumn, the remaining 10 percent of the population suffer from hay fever or pollen asthma. The link between the nose and the airways is obvious. Anyone who suffers from hay fever, called pollinosis in medical terminology, will complain about the discomfort it causes. While everyone else enjoys the first signs of summer, the sunshine, the warmth and the blooming of the meadows, the person suffering from hay fever hides behind the drawn blinds because otherwise, his eyes run and the itching of the eye becomes intolerable. A person suffering from hay fever may also experience a constantly running nose, difficulty of breathing through the nose and may feel generally ill although the illness seems to be so harmless.
Nonetheless, the person with hay fever suffers far less than the one with pollen asthma. Pollen asthma affects a part of the bronchial system, which is far more important for breathing than is the nose. It is not known why the disease affects the nose in one person and the bronchial system in another. Unfortunately, children who suffer from hay fever while still in school develop asthma as adults. Causes for this development are unknown.
How does the seemingly innocuous pollen cause asthma?
Pollen is usually too large to infiltrate the bronchial wall as a whole. Rather, the bronchial mucosa dissolves the pollen into protein particles small enough to pass through the epithelium (a membranous tissue composed of cell layers forming the covering of most internal and external surfaces of the body and its organs). These pollen particles then encounter cells in the bronchial mucosa, which develop antibodies against it. It would appear that this formation of antibodies to trap the pollen particles is normal. Unfortunately, the antibody struggles with the intruding pollen particle without success. The formation of allergy antibodies initiates a reaction, which is more harmful to the body than if nothing had happened. The struggle between the intruding allergens and the antibodies formed by the body takes place on the membrane of so-called mast cells, which are composed of dangerous substances. Mast cells take part in the body's allergic response. They can be found in most body tissues, but are predominantly abundant in connective tissue, such as the bronchial mucosa. In an allergic response, an allergen stimulates the release of antibodies, which attach themselves to mast cells. Following subsequent allergen exposure, the mast cells release substances such as histamine (a chemical which causes allergic symptoms) into the tissue. These substances lead to a spasm of the bronchial muscles, make the small vessels in the bronchial mucosa permeable, allow blood plasma to escape into the tissue and lead to the production of extremely viscid bronchial mucus.
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