Podcast
Questions and Answers
What characterizes Type I hypersensitivity reactions?
What characterizes Type I hypersensitivity reactions?
- Delayed response occurring 48-72 hours after exposure.
- IgE production leads to mast cell degranulation. (correct)
- IgG is produced in response to the allergen.
- It involves cytotoxic reactions to self-antigens.
Which of the following statements about Type II hypersensitivity is incorrect?
Which of the following statements about Type II hypersensitivity is incorrect?
- It involves immune responses to self-antigens.
- Complement activation is a key feature of this type.
- Examples include hemolytic diseases of newborns.
- It is characterized by the production of IgE antibodies. (correct)
How do immune complex diseases, classified as Type III hypersensitivity, primarily cause tissue injury?
How do immune complex diseases, classified as Type III hypersensitivity, primarily cause tissue injury?
- By inducing an immediate anaphylactic reaction.
- By stimulating excessive IgE production in response to antigens.
- By direct cell lysis via cytotoxic T cells.
- By depositing antigen-antibody complexes in blood vessels. (correct)
Which of the following examples is associated with Type IV hypersensitivity?
Which of the following examples is associated with Type IV hypersensitivity?
Which of the following best describes the mechanism underlying anaphylaxis?
Which of the following best describes the mechanism underlying anaphylaxis?
What distinguishes Type IV hypersensitivity from other types?
What distinguishes Type IV hypersensitivity from other types?
Which of the following occurs in Type II hypersensitivity?
Which of the following occurs in Type II hypersensitivity?
Which of the following allergens is most likely associated with Type I hypersensitivity?
Which of the following allergens is most likely associated with Type I hypersensitivity?
What is the primary immunoglobulin involved in Type I hypersensitivity reactions?
What is the primary immunoglobulin involved in Type I hypersensitivity reactions?
Which type of hypersensitivity involves a response to one's own tissues?
Which type of hypersensitivity involves a response to one's own tissues?
What is a common clinical manifestation of systemic Type I hypersensitivity?
What is a common clinical manifestation of systemic Type I hypersensitivity?
Which condition is an example of Type III hypersensitivity?
Which condition is an example of Type III hypersensitivity?
What is the typical time frame for a Type IV hypersensitivity reaction to manifest?
What is the typical time frame for a Type IV hypersensitivity reaction to manifest?
Which of the following best describes the underlying mechanism of Type III hypersensitivity?
Which of the following best describes the underlying mechanism of Type III hypersensitivity?
Which statement accurately describes one of the mechanisms involved in Type II hypersensitivity?
Which statement accurately describes one of the mechanisms involved in Type II hypersensitivity?
What process is primarily responsible for tissue injury in Type III hypersensitivity?
What process is primarily responsible for tissue injury in Type III hypersensitivity?
What type of hypersensitivity is associated with delayed contact dermatitis from substances like poison ivy?
What type of hypersensitivity is associated with delayed contact dermatitis from substances like poison ivy?
Which of the following is NOT a mechanism involved in Type II hypersensitivity?
Which of the following is NOT a mechanism involved in Type II hypersensitivity?
Study Notes
Definition of Hypersensitivity
- Increased immune response to antigens leading to undesirable clinical effects.
- Four types of hypersensitivity reactions can occur simultaneously, not in isolation.
Type I – Immediate Hypersensitivity (Atopy)
- Characterized by the production of IgE antibodies instead of IgG.
- Triggered by allergen exposure, leading to:
- Mast cell degranulation.
- Release of histamine.
- Allergens are usually harmless substances, including:
- Shellfish
- Pet dander
- Dust mites
- Peanuts
- Latex
- Insect venom.
- Anaphylaxis occurs as a systemic Type I response.
Type II – Cytotoxic Reactions to Self-Antigens
- Immune attack on one’s own tissues.
- Mechanisms involved include:
- Complement activation
- Agglutination
- Phagocytosis.
- Examples are:
- Hemolytic diseases of the newborn.
- Myasthenia gravis.
- Cross-reactions between exogenous and endogenous tissues may occur:
- Hemolytic streptococci linked to mitral valve disease.
- Guillain-Barre syndrome.
Type III – Immune Complex Diseases
- Involves deposition of antigen-antibody complexes around small blood vessels.
- Leads to complement cascade activation, acute inflammation, and tissue injury.
- Conditions associated include:
- Rheumatoid arthritis.
- Nephritis.
- Pericarditis.
- Vasculitis, notably systemic lupus erythematosus where the cell nucleus is the antigen.
Type IV – Cell-Mediated Immunity
- Presents as a delayed reaction to allergens, typically occurring 48-72 hours after exposure.
- Involves interactions between macrophages and T-cells which require time to develop.
- Common examples include:
- Transplant rejections.
- Delayed contact dermatitis, such as reactions to poison ivy.
Definition of Hypersensitivity
- Increased immune response to antigens leading to undesirable clinical effects.
- Four types of hypersensitivity reactions can occur simultaneously, not in isolation.
Type I – Immediate Hypersensitivity (Atopy)
- Characterized by the production of IgE antibodies instead of IgG.
- Triggered by allergen exposure, leading to:
- Mast cell degranulation.
- Release of histamine.
- Allergens are usually harmless substances, including:
- Shellfish
- Pet dander
- Dust mites
- Peanuts
- Latex
- Insect venom.
- Anaphylaxis occurs as a systemic Type I response.
Type II – Cytotoxic Reactions to Self-Antigens
- Immune attack on one’s own tissues.
- Mechanisms involved include:
- Complement activation
- Agglutination
- Phagocytosis.
- Examples are:
- Hemolytic diseases of the newborn.
- Myasthenia gravis.
- Cross-reactions between exogenous and endogenous tissues may occur:
- Hemolytic streptococci linked to mitral valve disease.
- Guillain-Barre syndrome.
Type III – Immune Complex Diseases
- Involves deposition of antigen-antibody complexes around small blood vessels.
- Leads to complement cascade activation, acute inflammation, and tissue injury.
- Conditions associated include:
- Rheumatoid arthritis.
- Nephritis.
- Pericarditis.
- Vasculitis, notably systemic lupus erythematosus where the cell nucleus is the antigen.
Type IV – Cell-Mediated Immunity
- Presents as a delayed reaction to allergens, typically occurring 48-72 hours after exposure.
- Involves interactions between macrophages and T-cells which require time to develop.
- Common examples include:
- Transplant rejections.
- Delayed contact dermatitis, such as reactions to poison ivy.
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Description
This quiz provides an overview of hypersensitivity, defining the concept and detailing the four types of hypersensitivity reactions. It highlights the immune system's increased response to antigens and discusses the specific characteristics, including time courses and immunoglobulin involvement. Perfect for students studying immunology or related fields.
