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Questions and Answers
What type of hypersensitivity reaction is mediated by IgE antibodies?
What type of hypersensitivity reaction is mediated by IgE antibodies?
- Type I (correct)
- Type II
- Type III
- Type IV
Which of the following is NOT a result of a Type I hypersensitivity reaction?
Which of the following is NOT a result of a Type I hypersensitivity reaction?
- Hay fever
- Bronchial asthma
- Anaphylactic shock
- Autoimmune disease (correct)
Which statement correctly describes the mediators involved in hypersensitivity reactions?
Which statement correctly describes the mediators involved in hypersensitivity reactions?
- Type II hypersensitivity is the only type that causes anaphylactic shock.
- Type III hypersensitivity is exclusively cell mediated.
- Type IV hypersensitivity does not involve antibodies. (correct)
- Type I hypersensitivity is primarily caused by IgM antibodies.
What occurs during the first exposure to an allergen in a Type I hypersensitivity reaction?
What occurs during the first exposure to an allergen in a Type I hypersensitivity reaction?
What mechanism leads to the release of mediators in a Type I hypersensitivity reaction upon re-exposure to an allergen?
What mechanism leads to the release of mediators in a Type I hypersensitivity reaction upon re-exposure to an allergen?
Which of the following statements correctly identifies a role of cytokines produced by activated mast cells?
Which of the following statements correctly identifies a role of cytokines produced by activated mast cells?
Which of the following is characteristic of Type II hypersensitivity reactions?
Which of the following is characteristic of Type II hypersensitivity reactions?
In which type of hypersensitivity are preformed mediators, such as histamine, released from mast cells?
In which type of hypersensitivity are preformed mediators, such as histamine, released from mast cells?
Which of the following substances is not classified as an ingestant?
Which of the following substances is not classified as an ingestant?
What indicates an allergic reaction during a skin test?
What indicates an allergic reaction during a skin test?
Which of the following is a method of drug therapy for allergies?
Which of the following is a method of drug therapy for allergies?
What is the result of Ig G or Ig M antibodies reacting with antigens in Type II hypersensitivity?
What is the result of Ig G or Ig M antibodies reacting with antigens in Type II hypersensitivity?
What type of antibody response occurs due to hyposensitization therapy?
What type of antibody response occurs due to hyposensitization therapy?
What mechanism is primarily responsible for cell lysis in Type II hypersensitivity reactions?
What mechanism is primarily responsible for cell lysis in Type II hypersensitivity reactions?
Which of the following best describes the role of total serum Ig E determination in allergy diagnosis?
Which of the following best describes the role of total serum Ig E determination in allergy diagnosis?
What is the expected outcome of the skin test indicating allergy to a specific allergen?
What is the expected outcome of the skin test indicating allergy to a specific allergen?
Which cells are primarily active in antibody-dependent cellular cytotoxicity (ADCC)?
Which cells are primarily active in antibody-dependent cellular cytotoxicity (ADCC)?
Which clinical condition is associated with cytotoxic reactions involving antibodies against muscle acetylcholine receptors?
Which clinical condition is associated with cytotoxic reactions involving antibodies against muscle acetylcholine receptors?
What triggers hyperacute graft rejection?
What triggers hyperacute graft rejection?
Which disorders exemplify non-cytotoxic Type II hypersensitivity?
Which disorders exemplify non-cytotoxic Type II hypersensitivity?
In Type III hypersensitivity reactions, what is the primary outcome of immune complex deposition?
In Type III hypersensitivity reactions, what is the primary outcome of immune complex deposition?
What type of antibodies form immune complexes in Type III hypersensitivity reactions?
What type of antibodies form immune complexes in Type III hypersensitivity reactions?
Which condition results from drug reactions where antibodies target cell-drug complexes?
Which condition results from drug reactions where antibodies target cell-drug complexes?
What is the main role of the reticuloendothelial system in Type III hypersensitivity?
What is the main role of the reticuloendothelial system in Type III hypersensitivity?
What is one consequence of platelet aggregation in the formation of antigen-antibody complexes?
What is one consequence of platelet aggregation in the formation of antigen-antibody complexes?
Which of the following best describes the function of anaphylatoxins released from complement activation?
Which of the following best describes the function of anaphylatoxins released from complement activation?
What type of immune response is characterized by persistent inflammation due to immune complexes?
What type of immune response is characterized by persistent inflammation due to immune complexes?
Which clinical condition is an example of a Type III hypersensitivity reaction?
Which clinical condition is an example of a Type III hypersensitivity reaction?
What is a primary factor contributing to the formation of immune complexes in Type III hypersensitivity?
What is a primary factor contributing to the formation of immune complexes in Type III hypersensitivity?
Which immune cells are primarily attracted to the site of immune complex deposition in Type III hypersensitivity?
Which immune cells are primarily attracted to the site of immune complex deposition in Type III hypersensitivity?
What is one of the consequences of histamine release during the immune complex response?
What is one of the consequences of histamine release during the immune complex response?
Which of the following is a classic prototype of a Type III hypersensitivity reaction?
Which of the following is a classic prototype of a Type III hypersensitivity reaction?
What is a systemic immune complex phenomenon that occurs after injection of large doses of foreign serum?
What is a systemic immune complex phenomenon that occurs after injection of large doses of foreign serum?
Which of the following symptoms is NOT typically associated with serum sickness?
Which of the following symptoms is NOT typically associated with serum sickness?
Which clinical condition is characterized by immune complex deposition in the lungs due to inhalation of dust or mold spores?
Which clinical condition is characterized by immune complex deposition in the lungs due to inhalation of dust or mold spores?
In Type IV hypersensitivity reactions, what cells are primarily involved in the cell-mediated immunity process?
In Type IV hypersensitivity reactions, what cells are primarily involved in the cell-mediated immunity process?
Which statement accurately describes the sequence of events in a Type IV hypersensitivity reaction?
Which statement accurately describes the sequence of events in a Type IV hypersensitivity reaction?
Which of the following is NOT an example of a condition associated with Type III hypersensitivity?
Which of the following is NOT an example of a condition associated with Type III hypersensitivity?
Immune complexes are deposited in small blood vessels leading to which of the following conditions?
Immune complexes are deposited in small blood vessels leading to which of the following conditions?
What type of hypersensitivity reaction is primarily mediated by antibodies?
What type of hypersensitivity reaction is primarily mediated by antibodies?
Study Notes
Hypersensitivity Reactions
- Defined as exaggerated immune responses that are harmful to the host.
Types of Hypersensitivity
- There are four types, categorized based on the primary mechanisms: Type I, Type II, Type III, and Type IV.
- Types I, II, and III involve antibody-mediated immune mechanisms.
- Type IV is cell-mediated, involving T cell activation and cytokine production.
Type I: Immediate Hypersensitivity
- Also known as anaphylaxis, this reaction is triggered by IgE antibodies.
- IgE binds to mast cells and basophils, leading to the release of various mediators upon antigen exposure.
- Mediators include histamine, leukotrienes, prostaglandins, and platelet-activating factor.
- Manifestations range from localized allergic responses (e.g., hay fever, food allergies) to systemic anaphylaxis (life-threatening).
- Diagnosis involves careful history-taking, skin tests to identify allergens, and measuring IgE levels.
- Management includes allergen avoidance, hyposensitization, and drug therapy (e.g., corticosteroids, epinephrine, antihistamines).
Type II: Cytotoxic or Cytolytic Reactions
- Mediated by IgG or IgM antibodies that target antigens on cell surfaces.
- These antibodies can trigger cell lysis through complement activation, enhance phagocytosis via opsonization, or promote antibody-dependent cellular cytotoxicity (ADCC).
- Clinical examples include ABO incompatibility reactions, Rh incompatibility leading to hemolytic disease of the newborn, autoimmune diseases (e.g., autoimmune hemolytic anemia, myasthenia gravis), and graft rejection.
Type III: Immune Complex Mediated Reaction
- Occurs when IgG or IgM antibodies complex with soluble antigens.
- Immune complexes can be deposited in tissues, primarily in the basement membranes of blood vessels, triggering inflammation.
- Clinical examples include Arthus reaction, serum sickness, post-streptococcal glomerulonephritis, hypersensitivity pneumonitis (e.g., farmer's lung), and some autoimmune diseases like systemic lupus erythematosus (SLE) and rheumatoid arthritis.
Type IV: Cell Mediated (Delayed Type) Hypersensitivity
- Distinguished from the immediate types (I-III) as it doesn't involve antibody directly.
- It is a cell-mediated response driven by T cells and cytokines.
- This type of hypersensitivity is characterized by a delayed reaction (hours to days) after antigen exposure.
- Examples include contact dermatitis (e.g., poison ivy), tuberculin reaction, graft rejection, and autoimmune diseases involving T cell-mediated tissue damage.
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Description
This quiz provides an overview of hypersensitivity reactions, including their definition and the four types categorized by immune response mechanisms. It delves into Type I hypersensitivity, discussing its triggers, mediators, and management strategies. Test your understanding of these crucial immunological concepts.
