Final answer:
The correct spelling for a reaction characterized by an exaggerated immune response to a harmless substance is 'allergic.' An allergy is a Type I hypersensitivity, and exposure to allergens like pollen results in an immediate hypersensitivity reaction. This is important for diagnosis and management of allergic conditions.
Step-by-step explanation:
Correct Spelling of Allergic Reactions
The correct term for being characterized by an exaggerated reaction to an antigen or toxin is allergic. In an allergy, an individual's immune system overreacts to a harmless substance known as an allergen. This type of immune system response is known as a Type I hypersensitivity. Such allergens can include everyday items like pollen, animal dander, or certain foods. People who are allergic to these substances produce IgE antibodies upon the first encounter with the allergen. These antibodies then sensitize the individual to the allergen. On subsequent exposure, this leads to immediate hypersensitivity, causing symptoms that can range from mild, such as sneezing or itchy eyes, to severe reactions like anaphylactic shock. It is essential to understand these reactions as they can significantly impact individuals who experience them.
Answering the questions, an allergy to pollen is classified as immediate hypersensitivity, and a potential cause of acquired autoimmunity could be molecular mimicry. Allergic responses are specific antibody-mediated immune responses that occur within minutes after exposure to an allergen. Therefore, immediate hypersensitivities such as an allergy to pollens are crucial to recognize for proper diagnosis and treatment.