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Questions and Answers
What characterizes Type I hypersensitivity reactions?
What characterizes Type I hypersensitivity reactions?
How is immediate hypersensitivity defined?
How is immediate hypersensitivity defined?
Which type of hypersensitivity involves IgG antibodies?
Which type of hypersensitivity involves IgG antibodies?
Delayed hypersensitivity reactions occur within what timeframe?
Delayed hypersensitivity reactions occur within what timeframe?
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What is the mechanism primarily responsible for tissue injury in Type I hypersensitivity?
What is the mechanism primarily responsible for tissue injury in Type I hypersensitivity?
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Which hypersensitivity reaction classification is based on time of response?
Which hypersensitivity reaction classification is based on time of response?
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Which immunological mechanism is mainly responsible for Type II hypersensitivity?
Which immunological mechanism is mainly responsible for Type II hypersensitivity?
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Why is the classification of hypersensitivity by time considered outdated?
Why is the classification of hypersensitivity by time considered outdated?
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What correctly describes the outcome of neutrophil activation in response to immune complexes?
What correctly describes the outcome of neutrophil activation in response to immune complexes?
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Which type of hypersensitivity reaction is characterized primarily by an IgE and mast cell-mediated process?
Which type of hypersensitivity reaction is characterized primarily by an IgE and mast cell-mediated process?
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In type 3 hypersensitivity, what happens when soluble antigens bind to antibodies?
In type 3 hypersensitivity, what happens when soluble antigens bind to antibodies?
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Which of the following best describes the acronym ACID in the context of hypersensitivity reactions?
Which of the following best describes the acronym ACID in the context of hypersensitivity reactions?
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What role do Fc gamma receptors on neutrophils play in the immune response?
What role do Fc gamma receptors on neutrophils play in the immune response?
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What is a potential consequence of activated complement pathways in hypersensitivity reactions?
What is a potential consequence of activated complement pathways in hypersensitivity reactions?
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In type 4 hypersensitivity reactions, which cells are primarily involved?
In type 4 hypersensitivity reactions, which cells are primarily involved?
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What is the primary event that occurs in anaphylaxis?
What is the primary event that occurs in anaphylaxis?
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What role do cytokines play in anaphylaxis?
What role do cytokines play in anaphylaxis?
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Which of the following symptoms is primarily caused by laryngeal edema during anaphylaxis?
Which of the following symptoms is primarily caused by laryngeal edema during anaphylaxis?
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What is meant by the term 'iatrogenic' in the context of anaphylaxis?
What is meant by the term 'iatrogenic' in the context of anaphylaxis?
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What is a common allergen associated with anaphylaxis?
What is a common allergen associated with anaphylaxis?
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Which immune cell is NOT directly involved in the release of cytokines that contribute to tissue damage during anaphylaxis?
Which immune cell is NOT directly involved in the release of cytokines that contribute to tissue damage during anaphylaxis?
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Which manifestation is an example of local type I hypersensitivity?
Which manifestation is an example of local type I hypersensitivity?
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What sound might be heard when a person is wheezing during an anaphylactic episode?
What sound might be heard when a person is wheezing during an anaphylactic episode?
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What causes increased intestinal motility during anaphylaxis?
What causes increased intestinal motility during anaphylaxis?
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What characterizes hay fever?
What characterizes hay fever?
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Which statement about anaphylaxis is accurate?
Which statement about anaphylaxis is accurate?
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Which of the following conditions is NOT classified as a type 1 reaction?
Which of the following conditions is NOT classified as a type 1 reaction?
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What role does genetic predisposition play in immediate hypersensitivity?
What role does genetic predisposition play in immediate hypersensitivity?
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What initiates a type 1 hypersensitivity reaction?
What initiates a type 1 hypersensitivity reaction?
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Which of these is an example of a typical allergen?
Which of these is an example of a typical allergen?
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What is a common symptom of food allergies related to type 1 hypersensitivity?
What is a common symptom of food allergies related to type 1 hypersensitivity?
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How does bronchial asthma manifest in individuals with a type 1 hypersensitivity?
How does bronchial asthma manifest in individuals with a type 1 hypersensitivity?
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What is a common cause of conjunctivitis related to allergens?
What is a common cause of conjunctivitis related to allergens?
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Which condition forms part of the atopic triad?
Which condition forms part of the atopic triad?
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What protein's mutation increases the risk of atopic dermatitis?
What protein's mutation increases the risk of atopic dermatitis?
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What type of asthma may not be associated with IgE?
What type of asthma may not be associated with IgE?
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What mediators are involved in the late phase reaction of asthma?
What mediators are involved in the late phase reaction of asthma?
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Which of the following is NOT a factor contributing to seasonal allergic rhinitis?
Which of the following is NOT a factor contributing to seasonal allergic rhinitis?
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What triggers bronchial asthma?
What triggers bronchial asthma?
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What can lead to excessive mucus production in asthma?
What can lead to excessive mucus production in asthma?
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Which receptor is responsible for mediating vasodilation and increased vascular permeability due to histamine?
Which receptor is responsible for mediating vasodilation and increased vascular permeability due to histamine?
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What is the main action of corticosteroids in immunosuppressive therapy?
What is the main action of corticosteroids in immunosuppressive therapy?
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Which of the following cytokines is primarily responsible for increasing mucus secretion during immediate hypersensitivity reactions?
Which of the following cytokines is primarily responsible for increasing mucus secretion during immediate hypersensitivity reactions?
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Which drug is considered a mast cell stabilizer?
Which drug is considered a mast cell stabilizer?
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What mechanism do H2 receptor blockers primarily utilize?
What mechanism do H2 receptor blockers primarily utilize?
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Which of the following is not a preformed mediator found in mast cells?
Which of the following is not a preformed mediator found in mast cells?
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What is the process called that involves repeated administration of small doses of an allergen to induce tolerance?
What is the process called that involves repeated administration of small doses of an allergen to induce tolerance?
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What effect do humanized monoclonal anti-IgE antibodies have on the immune response?
What effect do humanized monoclonal anti-IgE antibodies have on the immune response?
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Study Notes
Hypersensitivity Overview
- Hypersensitivity is an exaggerated or aberrant immune response to a substance, leading to tissue damage
- Hypersensitivity reactions are classified into four types based on the immune mechanisms involved
- Type I hypersensitivity is mediated by IgE antibodies, resulting in immediate reactions
- Type II hypersensitivity involves antibodies targeting cell surface antigens, resulting in cytotoxic reactions
- Type III hypersensitivity is characterized by the formation of immune complexes that deposit in tissues, causing inflammatory reactions
- Type IV hypersensitivity is mediated by T lymphocytes, resulting in delayed reactions
Type I Hypersensitivity (Immediate)
- Initiated by the production of IgE antibodies against environmental antigens (allergens)
- IgE binds to mast cells and basophils
- Subsequent exposure to allergen cross-links IgE on mast cells
- This triggers degranulation and release of mediators like histamine, leukotrienes, and prostaglandins
- Mediators cause vasodilation, increased vascular permeability, smooth muscle contraction, and inflammation
- Examples include allergic rhinitis, asthma, food allergies, and anaphylaxis
Type II Hypersensitivity (Antibody-Mediated Cytotoxic)
- Antibodies (IgG or IgM) directly target cell surface antigens or extracellular matrix components
- This can lead to cell destruction via complement activation, opsonization, or antibody-dependent cell-mediated cytotoxicity (ADCC)
- Examples include transfusion reactions, autoimmune hemolytic anemia, and some forms of myasthenia gravis
Type III Hypersensitivity (Immune Complex-Mediated)
- Formation of antigen-antibody complexes in the circulation
- These complexes deposit in tissues, activating complement, attracting neutrophils and other inflammatory cells, causing inflammation and tissue damage
- Examples include serum sickness, lupus nephritis, and rheumatoid arthritis
Type IV Hypersensitivity (Cell-Mediated)
- Mediated by T cells, not antibodies
- Reactions develop over several hours or days
- Primarily T cells are activated and release cytokines
- Cytokines cause inflammation and recruitment of other immune cells, resulting in tissue damage
- Examples include contact dermatitis, tuberculin skin test, and some autoimmune diseases
Learning Objectives (of Course)
- Hypersensitivity, allergy, atopy, classification of hypersensitivity reactions
- Type I hypersensitivity reaction, mechanisms, role of IgE
- Anaphylaxis, local manifestations (asthma, hay fever, eczema), allergic reactions
- Treatment of immediate hypersensitivity reactions
Mechanisms and Mediators
- Mast cells release preformed mediators (e.g., histamine, proteases) and lipid mediators (e.g., prostaglandins, leukotrienes) after exposure to allergen
- Cytokines (e.g., TNF, IL-4) contribute to the late phase of the reaction by attracting neutrophils and eosinophils
Quiz Questions
- Q1: Cytokines are responsible for late-phase reactions in Type I hypersensitivity
- Q2: Cromolyn Na is a mast cell stabilizer
- Q3: IL-4, IL-13, and IL-5 are cytokines that stimulate mucus secretion
- Q4: Prostaglandins are preformed mediators
Anaphylaxis, Atopy, Allergy
- Systemic form of immediate hypersensitivity is anaphylaxis
- Common allergens include drugs (like penicillin), insect stings, ingested foods (shellfish, nuts), and some other factors
- Manifestations include breathing problems, circulatory problems, skin rashes, swelling and possible death if left untreated
- Atopy is a familial predisposition to developing hypersensitivity reactions
- Allergy is hypersensitivity to harmless substances (allergens), typically Type I
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Description
Test your knowledge on the different types of hypersensitivity reactions including Type I, Type II, and Type III. This quiz covers the mechanisms, definitions, and outcomes associated with immediate and delayed hypersensitivity. Ideal for students studying immunology or related fields.
