GED Science TestLife ScienceMedium
A patient experiences a sudden, severe allergic reaction after being stung by a bee. Symptoms include widespread hives, swelling of the face and throat, difficulty breathing, and a rapid drop in blood pressure. Which type of immune response is this patient exhibiting?
- AAutoimmune response
- BType I hypersensitivity (anaphylaxis)
- CCell-mediated immunity
- DDelayed-type hypersensitivity
Show answer & explanationAnswer & explanation
Correct answer: B. Type I hypersensitivity (anaphylaxis)
The described symptoms—hives, swelling, difficulty breathing, and a drop in blood pressure—are characteristic of anaphylaxis, which is a severe, systemic Type I hypersensitivity reaction. This response is mediated by IgE antibodies and histamine release.
Why the other options are wrong
- A. An autoimmune response occurs when the immune system mistakenly attacks the body's own tissues, not an external allergen.
- C. Cell-mediated immunity involves T cells and is responsible for fighting intracellular pathogens and cancer, not immediate allergic reactions.
- D. Delayed-type hypersensitivity (Type IV) reactions are T-cell mediated and develop 24-72 hours after antigen exposure, such as in contact dermatitis.
Type I Hypersensitivity (Anaphylaxis)
A rapid and severe allergic reaction mediated by IgE antibodies, leading to the release of histamine and other inflammatory mediators, causing symptoms like swelling, hives, bronchoconstriction, and hypotension.
- Mediated by IgE antibodies.
- Involves mast cells and basophils.
- Can be life-threatening.
- Common triggers include insect stings, foods, medications.
Memory trick: ACID: Anaphylactic, Cytotoxic, Immune complex, Delayed.