Paper I — 2023 March (Supplementary) (2010 Scheme) — Q12
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Paper I
2023 March (Supplementary) (2010 Scheme) · 40 marks · 120 min
Question
Give two examples of mediators of type I hypersensitivity.
Q122 marksShort Notes
Answer
Two examples of mediators of Type I hypersensitivity (released on mast cell/basophil degranulation following IgE cross-linking):
Histamine — a preformed mediator, causes vasodilation, increased vascular permeability, smooth muscle contraction (bronchospasm), and increased mucus secretion, acting via H1 receptors; the principal mediator of the immediate reaction.
Leukotrienes (e.g., LTC4, LTD4, LTE4 — collectively the “slow-reacting substance of anaphylaxis”) — newly synthesized mediators derived from arachidonic acid metabolism, causing more prolonged bronchoconstriction and increased vascular permeability, contributing to the late-phase reaction.
