Allergy: Test Your Understanding
Teacher's Guide
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What is the difference between an allergen and an antigen?
An antigen is a substance that causes the immune system to produce specific antibodies against it.
An allergen is a type of antigen that produces an exaggerated physiologic response in animals,
including humans.
What are the three principle types of immune responses to allergens?
The three principle types of immune responses are production of immunoglobulin E (IgE) antibodies, IgG
or IgM antibodies, and sensitized lymphocytes.
Name five clinical manifestations of allergies.
Clinical manifestations of allergies include allergic rhinitis (hay fever), bronchial asthma, hives, atopic
(endogenous) eczema (atopic dermatitis) and other eczematous skin lesions, and anaphylactic shock.
Critical Thinking: In medicine, the hygiene hypothesis posits that hygienic conditions—such as requiring
children to frequently use hand sanitizers—create more allergies, because exposure to allergens can "train"
the body's immune system to better manage allergic responses. Choose a side and present an argument for
or against the hygiene hypothesis.
Sample answer: I agree with the hygiene hypothesis, because people in developed countries tend to have
more allergies—especially food allergies and bronchial asthma—than people in underdeveloped or de-
veloping countries, where hygienic conditions are less prevalent. By removing natural "germs" and "dirt"
in the environment, you potential disallow a child's developing immune system the ability to naturally
desensitize to potential allergens.
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