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CHILDREN’S ALLERGY: EXPLANATION OF TERMS

Millions of years ago, a child was born whose body did not understand the difference between harmless substances normally found in the environment (allergens) and agents that carried infections. As a result, the child reacted to allergens in the same way he reacted to infections-by producing antibodies (protective substances) against them. With these new antibodies, he fought the allergens in various organs of his body, causing an inflammation there. This inflammation is known as allergy. As allergic men and women got married, this weakness was compounded in their offspring. They became known as allergy-prone or atopic children.

Explanation of Terms

Atopy (or allergy proneness). This is susceptibility to a group of illnesses that develop naturally after contact with allergens. It has the following characteristics:

a. A family history of allergy. An atopic child will not inherit a specific allergic disease. He does inherit, however, the tendency to develop sensitivity to any allergen when he comes in contact with it. This contact cannot be avoided realistically, and it may take place months or years after birth.

b. A reaction to an injected allergen. This may be a swelling and an itch in the skin where an allergen, to which one is sensitive, has been injected.

Sensitization. When an atopic child is exposed to an allergen, he may become sensitive to it. Sensitization can be active or passive. An example of active sensitization is when an allergic child develops allergy to ragweed when he is exposed to it. An example of passive sensitization is illustrated in the following historic experiment. Blood serum from Dr. Kustner, who was sensitive to fish, was injected into the skin of Dr. Prausnitz, who was not. A few hours later, an extract of fish was injected into the skin of Dr. Prausnitz. Within thirty minutes, an inflammation and itching developed in the skin of Dr. Prausnitz, who had never before been sensitive to fish. The skin of Dr. Prausnitz, which did not contain antibodies against fish, acquired them through a passive transfer from Dr. Kustner’s blood serum, which did contain them. Passive transfer causes a local sensitivity that lasts only a short time, in contrast to active sensitivity which lasts much longer.

Sensitization can be immediate or delayed. One child may develop hay fever minutes after exposure to ragweed; this is an immediate type of sensitivity. Another child may develop poison ivy dermatitis days after exposure to poison ivy; this is the delayed type of sensitivity. The distinction between the two kinds of sensitivity is based upon the time required for an allergic reaction to develop following exposure to an allergen.

Some factors influence the type and likelihood of allergy:

a.     The route through which the allergen enters the body. Some allergens are more dangerous when given by injection and less dangerous when given by mouth. An example is penicillin.

b.     The presence of the allergen in the environment in quantity. Ragweed may cause allergies in children while they are in America because ragweed is present in abundance here; it does not cause allergies in the same children when they are in Europe because it is less abundant there.

ñ     Some substances have a stronger allergenic power than others and are therefore more likely to cause an allergy. The egg white has stronger allergenic power than the yolk,

d.     The capacity of a person to acquire an allergy. Twins growing up in the same environment may develop different kinds of allergies; also, one twin may develop an allergy, while the other may never develop an allergy.

Toxicity. Toxicity is not allergy; it is the reaction of the body to a substance given to it in quantity (such as the reaction of a person who is stung by many bees). Allergy, on the other hand, may result from an injection of a very small quantity of bee venom. Therefore, one definition of allergy would be an extreme sensitivity to a substance which is harmless to most persons when given to them in the same amount.

Shock Organ. The organ of the body which becomes inflamed in allergy is called the shock organ. In asthma, the shock organ is the lung; in hay fever, it is the nose; in eczema, it is the skin.

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