Podcast Beta
Questions and Answers
What is the main immune mediator involved in type II hypersensitivity reactions?
Which of the following is NOT a clinical example of type II hypersensitivity?
What characterizes type III hypersensitivity reactions compared to type II?
What is the main immunologic component involved in Type I hypersensitivity reactions?
Signup and view all the answers
What is the role of complement in type II hypersensitivity?
Signup and view all the answers
What mechanism is primarily responsible for the damage in serum sickness?
Signup and view all the answers
Which of the following is NOT a clinical manifestation of Type I hypersensitivity?
Signup and view all the answers
What is the timing of symptoms in type IV hypersensitivity?
Signup and view all the answers
What feature distinguishes Type I hypersensitivity from other types?
Signup and view all the answers
Which of the following statements about the Arthus reaction is true?
Signup and view all the answers
Which test is considered the preferred screening method for Type I hypersensitivity?
Signup and view all the answers
Which of the following is a characteristic of the immune mechanism in Type I hypersensitivity reactions?
Signup and view all the answers
Which component is involved in the immune mechanism of type II hypersensitivity that leads to cell function inhibition?
Signup and view all the answers
What type of antigens trigger Type I hypersensitivity reactions?
Signup and view all the answers
What is the timing of reactions in Type I hypersensitivity?
Signup and view all the answers
Type II hypersensitivity is primarily characterized by which type of immune response?
Signup and view all the answers
Study Notes
Hypersensitivity
- An exaggerated response to a typically harmless antigen that results in tissue injury, disease, or even death.
- Gell and Coombs classified hypersensitivity reactions into four types based on the immunologic mechanism involved, the antibody, and the nature of the triggering antigen.
- Antibody-mediated: Type I, II, and III
- Cell-mediated: Type IV
Type I Hypersensitivity
- Commonly referred as allergies
- The antigens that trigger type I hypersensitivities are called allergens.
- Distinguishing features: Short time lag phase.
- Key Immunologic Components:
- IgE
- Basophils
- Mast cells
- Eosinophils
Type I Hypersensitivity Reaction
- Immune Mediator: IgE
- Synonym: Anaphylactic
- Timing: Immediate
- Antigen: Heterologous
- Complement Involvement: No
- Immune Mechanism: Release of mediators from IgE-sensitized mast cells and basophils.
- Clinical Examples:
- Anaphylaxis
- Allergic Rhinitis
- Allergic Asthma
- Food Allergies
- Urticaria
Tests for Type I Hypersensitivity
-
In Vivo Skin Prick Test:
- Preferred screening test for allergies.
- Very small amounts of potential allergens are injected under the skin.
- Positive result: Wheal-and-flare reaction after 20 minutes.
-
Radioallergosorbent Test (RAST):
- A form of radioimmunoassay.
- A form of allergen-specific IgE testing.
-
Radioimmunosorbent Test (RIST):
- First test developed for the measurement of total IgE.
Type II Hypersensitivity
- Also known as antibody-mediated cytotoxic hypersensitivity.
- Involves IgG and IgM antibodies directed against antigens found on cell surfaces.
Type II Hypersensitivity Reaction
- Immune Mediator: IgG or IgM.
- Synonym: Antibody-mediated cytotoxicity.
- Timing: Immediate.
- Antigen: Autologous or heterologous, found on the cell surface.
- Complement Involvement: Yes.
- Immune Mechanism: Cell destruction caused by antibody and complement, opsonization, ADCC. Cell function inhibited by antibody binding.
- Clinical Examples:
- Transfusion reactions
- Autoimmune hemolytic anemia
- Hemolytic disease of the newborn
- Drug reactions
- Myasthenia gravis
- Goodpasture's syndrome
- Graves' disease
Type III Hypersensitivity
- Also known as immune complex hypersensitivity.
- Similar to Type II, but antigens are soluble.
Type III Hypersensitivity Reaction
- Immune Mediator: IgG or IgM.
- Synonym: Complex-mediated.
- Timing: Immediate.
- Antigen: Soluble, heterologous or autologous.
- Complement Involvement: Yes.
- Immune Mechanism: Antigen-antibody complex activates complement proteins. Neutrophils are recruited and release lysosomal enzymes causing tissue damage.
- Clinical Examples:
- Serum sickness
- Arthus reaction
- Lupus erythematosus
- Rheumatoid arthritis
- Drug reactions
Arthus Reaction
- Immune complexes formed deposit on the walls of blood vessels, activating complement.
Serum Sickness
- Results from passive immunization of humans with animal serum.
- Humans develop antibodies against protein in the animal serum, antibodies combine with the protein forming complexes that can deposit in the tissues.
Type IV Hypersensitivity
- First described by Robert Koch.
- Sensitized T cells, rather than antibodies, play a major role.
- Also known as delayed hypersensitivity because symptoms peak between 48-72 hours.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the fascinating world of hypersensitivity, particularly focusing on Type I reactions, commonly known as allergies. This quiz covers the classification of hypersensitivity and key immunologic components involved in allergic reactions, including the roles of IgE, mast cells, and basophils.
