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Questions and Answers
What is the primary function of Human Leukocyte Antigens (HLA) in the immune system?
Which phase of acute inflammation is characterized by vasodilation and increased permeability?
Why is matching Human Leukocyte Antigens (HLA) critical in transplantation?
What is the main consequence of HLA mismatch in organ transplantation?
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Which of the following statements about the cellular phase of acute inflammation is accurate?
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What is the primary immunoglobulin involved in Type I hypersensitivity reactions?
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Which of the following best describes Type II hypersensitivity?
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In Type I hypersensitivity, which immune cells are activated by the interaction of allergens and IgE antibodies?
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What is a key characteristic that distinguishes Type III hypersensitivity from other types?
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Which of the following substances is released from mast cells during an allergic reaction in Type I hypersensitivity?
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What is the role of plasma cells in the immune response involved in Type I hypersensitivity?
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What type of immune response is characteristic of Type IV hypersensitivity?
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Which of the following reactions is classified under Type II hypersensitivity?
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What is the primary mechanism through which Type IV Hypersensitivity causes tissue injury?
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Which type of hypersensitivity is primarily associated with the formation of immune complexes?
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What triggers the initiation of allergic rhinitis in susceptible individuals?
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What role do cytokines play in Type IV Hypersensitivity?
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In rheumatoid arthritis, which component is mistakenly identified as a foreign antigen by the immune system?
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Which symptom is NOT typically associated with Type IV Hypersensitivity reactions such as contact dermatitis?
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What is the end result of B-cell class switching in the context of allergic rhinitis?
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What is the typical time frame for the development of symptoms in Type IV Hypersensitivity reactions?
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Which type of hypersensitivity reaction is associated with Contact Dermatitis?
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What are the primary symptoms of food allergies in children?
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What role does IgE play in allergic reactions?
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How is a diagnosis of food allergies typically established?
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What is the major difference between systemic and local reactions in food allergies?
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Which of the following is NOT typically recognized as a common allergen for allergic rhinitis?
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What processes are involved in the sensitization phase of contact dermatitis?
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What symptom is most commonly associated with severe allergic rhinitis attacks?
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What is a key characteristic of an erythematous rash associated with contact dermatitis?
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During the vascular phase of acute inflammation, which response is observed first?
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Which factor primarily drives the chemotaxis of leukocytes to the site of injury?
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What typically initiates the symptoms of contact dermatitis after exposure to an offending agent?
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In the cellular phase of acute inflammation, what occurs after leukocyte margination?
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What is the primary function of the inflammatory response during acute inflammation?
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What is a common treatment approach for severe cases of contact dermatitis?
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Which process in phagocytosis involves the destruction of engulfed pathogens?
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Study Notes
Hypersensitivity
- An abnormal immune response that causes tissue damage.
- Classified into four types: Type I (IgE-mediated), Type II (antibody-mediated), Type III (immune complex mediated), and Type IV (T cell-mediated).
- Each type differs in the immune components, onset of symptoms, and mechanism of injury.
Type I Hypersensitivity
- Also known as allergic hypersensitivity.
- Depends on IgE-mediated activation of mast cells and basophils.
- Allergens, such as dust and animal hair, interact with B cell antibodies, triggering plasma cell production.
- Plasma cells produce IgE, which binds to mast cell surfaces.
- Mast cells release chemicals like histamine and bradykinin, causing anaphylactic responses, including airway constriction and vasodilation.
Type II Hypersensitivity
- Antibody-mediated or cytotoxic hypersensitivity.
- Involves IgG or IgM antibodies binding to tissue-specific antigens.
- Antigens can be intrinsic or extrinsic to the body.
- Clinical manifestations depend on the tissue expressing the target antigen.
Type III Hypersensitivity
- Immune complex-mediated hypersensitivity.
- Immune complexes form when antibodies bind to antigens, leading to tissue deposition and inflammation.
- Example: Rheumatoid arthritis, where autoantibodies against joint components form immune complexes that deposit in synovial membranes, causing inflammation, pain, and tissue damage.
Type IV Hypersensitivity
- Known as cell-mediated or delayed hypersensitivity.
- Requires time to develop.
- Involves sensitized T lymphocytes causing cell and tissue injury.
- T cells release cytokines that activate macrophages and cytotoxic T cells.
- Examples: contact dermatitis and type 1 diabetes.
Allergic Rhinitis
- A common hypersensitivity disorder of the upper respiratory tract.
- Type I allergic reaction mediated by IgE.
- Inhaled aeroallergens bind to IgE on mast cells in the nasal mucosa.
- This triggers the release of histamine and other inflammatory mediators, leading to symptoms like runny nose, nasal obstruction, sneezing, and watery eyes.
Food Allergies
- Caused by a Type allergic reaction.
- Common allergens include peanuts, tree nuts, shellfish, and milk.
- Food antigens interact with IgE in the mucous membranes, stimulating local and systemic cytokine and histamine release, leading to allergic reactions.
Contact Dermatitis
- Type IV hypersensitivity reaction.
- Caused by haptens (e.g., cosmetics, metals, topical drugs) that activate T lymphocytes in the skin.
- Sensitization phase: Haptens activate dendritic cells, which migrate to lymph nodes and stimulate T cell production.
- Elicitation phase: Re-exposure to the hapten triggers memory T cells, leading to cytokine release and inflammation.
Acute Inflammation
- An immediate and early response to injury that serves to control and eliminate harmful agents and promote tissue repair.
- Caused by infections, immune reactions, trauma, and tissue necrosis.
- Involves two phases: vascular and cellular.
Phases of Acute Inflammation
- Vascular Phase: Vasoconstriction followed by vasodilation, increased vascular permeability, and fluid movement out of blood vessels leading to swelling and pain.
- Cellular Phase: Leukocyte migration (adhesion, margination, transmigration) and chemotaxis to the site of injury.
Leukocyte Activation and Phagocytosis
- Leukocytes recognize, engulf, and kill harmful agents through phagocytosis.
Human Leukocyte Antigens (HLA)
- Proteins expressed on the surface of cells that allow the immune system to distinguish self from nonself.
- Matching HLA types between donor and recipient is crucial for successful organ transplantation to prevent rejection.
- HLA mismatch is a primary cause of alloreactive T-cell activation and graft rejection.
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Description
Explore the different types of hypersensitivity responses, including Type I and Type II. Understand the underlying immune mechanisms that lead to abnormal reactions and tissue damage. This quiz covers essential concepts regarding allergic and cytotoxic hypersensitivity, making it perfect for students in immunology or related fields.
