The type of hypersensitivity reaction due to IgE-mediated histamine release is called:

ESIC Nursing Officer -2019 (Shift -1)

Applied Microbiology & Infection control

Easy

Appeared in: ESIC Nursing Officer -2019 (Shift -1)

Explanation

Type 1 hypersensitivity is defined as a rapid, immediate immune response that occurs in a previously sensitized individual.
The reaction is mediated by Immunoglobulin E (IgE) antibodies, which are produced upon initial exposure to an allergen.
These IgE antibodies bind to the surface of mast cells and basophils.
Upon re-exposure, the allergen cross-links the IgE on these cells, triggering their degranulation and the release of potent inflammatory mediators, most notably histamine.
This process leads to the characteristic symptoms of an allergic reaction, such as vasodilation, itching, and smooth muscle contraction.

Option B: Type 2 hypersensitivity is a cytotoxic reaction, not an IgE-mediated one. It involves IgG or IgM antibodies that bind to antigens on the surface of cells, leading to cell destruction.
Option C: Type 4 hypersensitivity is a delayed, cell-mediated reaction. It does not involve antibodies like IgE but is instead driven by T-lymphocytes (T-cells).
Option D: Type 3 hypersensitivity is caused by the deposition of antigen-antibody (immune) complexes in tissues. These complexes involve IgG or IgM antibodies, not IgE, and they trigger an inflammatory response.

Visual 1: Diagram - Mechanism of Type 1 Hypersensitivity. This would show an allergen binding to IgE on a mast cell, triggering degranulation and histamine release.
Visual 2: Flowchart - Gell and Coombs Classification. A chart outlining the four types of hypersensitivity, their mediators, and example conditions.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of Hypersensitivity Reactions as background academic context rather than a clinical decision trigger.
A nurse must be able to rapidly identify signs of a severe Type 1 reaction, known as anaphylaxis. Symptoms include difficulty breathing, wheezing, hives, swelling of the face or throat, and a drop in blood pressure.
Immediate intervention for anaphylaxis is critical and includes administering epinephrine, maintaining the patient's airway (ABCs), providing oxygen, and establishing IV access for fluids and medications.
What if? If a patient presents with a skin rash 48 hours after starting a new medication, the nurse should suspect a Type 4 (delayed) hypersensitivity reaction, not a Type 1 reaction. The intervention would involve discontinuing the medication and providing supportive care, rather than immediate epinephrine.

How to Approach the Question

This is a factual recall question testing your knowledge of immunology.
Identify the key terms in the question: 'IgE-mediated' and 'histamine release'.
Recall the Gell and Coombs classification of hypersensitivity reactions.
Associate 'IgE' specifically with Type 1 (anaphylactic/atopic) reactions.
Eliminate the other options by recalling their mechanisms: Type 2 (cytotoxic, IgG/IgM), Type 3 (immune complex, IgG/IgM), and Type 4 (cell-mediated, T-cells).

Concept Tested & Keywords

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