Question:
Which of the following is the preformed mediator of inflammation?
Which of the following is the preformed mediator of inflammation?
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Vasoactive amines (Histamine and Serotonin) are the classic "ready-to-go" preformed mediators stored inside mast cell and platelet granules for immediate release during the early phase of acute inflammation.
Updated On: Aug 3, 2026
- Histamine
- Leukotrines
- Platelet activation factor
- The membrane attack complex
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Verified By Collegedunia
The Correct Option is A
Solution and Explanation
Step 1: Understanding the Concept:
Chemical mediators of inflammation are substances that initiate and regulate inflammatory reactions.
They are classified based on their origin as cell-derived (either preformed and stored in intracellular granules, or synthesized de novo) or plasma-protein-derived.
Step 2: Detailed Explanation:
Let us analyze each of the specified mediators:
- Histamine (A): This is a classic vasoactive amine. It is synthesized by mast cells, basophils, and platelets, and is stored as a preformed mediator inside intracellular secretory granules. Upon stimulation (such as physical injury, IgE binding, or complement activation), these cells undergo rapid degranulation, immediately releasing histamine to cause vasodilation and increased vascular permeability. Thus, histamine is a preformed mediator.
- Leukotrienes (B): These are arachidonic acid metabolites synthesized de novo (newly formed) via the lipoxygenase pathway during an inflammatory response. They are not stored preformed.
- Platelet-activating factor (C): This is a phospholipid-derived mediator generated de novo by various stimulated inflammatory cells. It is not stored preformed.
- The membrane attack complex (D): This is a multi-protein structure ($C5b-C9$) assembled on the surface of pathogen cell membranes as the end product of the complement cascade. It is plasma-derived and assembled dynamically, not stored preformed in cellular granules.
Therefore, histamine is the correct preformed cell-derived mediator.
Step 3: Final Answer:
The preformed mediator of inflammation is Histamine, which corresponds to option (A).
Chemical mediators of inflammation are substances that initiate and regulate inflammatory reactions.
They are classified based on their origin as cell-derived (either preformed and stored in intracellular granules, or synthesized de novo) or plasma-protein-derived.
Step 2: Detailed Explanation:
Let us analyze each of the specified mediators:
- Histamine (A): This is a classic vasoactive amine. It is synthesized by mast cells, basophils, and platelets, and is stored as a preformed mediator inside intracellular secretory granules. Upon stimulation (such as physical injury, IgE binding, or complement activation), these cells undergo rapid degranulation, immediately releasing histamine to cause vasodilation and increased vascular permeability. Thus, histamine is a preformed mediator.
- Leukotrienes (B): These are arachidonic acid metabolites synthesized de novo (newly formed) via the lipoxygenase pathway during an inflammatory response. They are not stored preformed.
- Platelet-activating factor (C): This is a phospholipid-derived mediator generated de novo by various stimulated inflammatory cells. It is not stored preformed.
- The membrane attack complex (D): This is a multi-protein structure ($C5b-C9$) assembled on the surface of pathogen cell membranes as the end product of the complement cascade. It is plasma-derived and assembled dynamically, not stored preformed in cellular granules.
Therefore, histamine is the correct preformed cell-derived mediator.
Step 3: Final Answer:
The preformed mediator of inflammation is Histamine, which corresponds to option (A).
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