In an allergic reaction, how do symptoms such as sneezing and swelling occur?
Answer and explanation
Correct answer: B. Allergen binds IgE on mast cells
- Step 1: An allergen is a harmless antigen that the immune system overreacts to.
- Step 2: On re-exposure it cross-links IgE on mast cells, causing histamine release, which widens blood vessels and causes swelling.
Answer
IgE on mast cells triggers histamine release.
Why not the others: Perforin is used by cytotoxic cells; insulin is not part of allergies; helper T cells do not make histamine.
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