Hypersensitivity Overview and Types
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Questions and Answers

What is the primary function of Human Leukocyte Antigens (HLA) in the immune system?

  • To facilitate T lymphocytes' recognition of foreign antigens (correct)
  • To promote phagocytosis of pathogens
  • To increase vascular permeability during inflammation
  • To inhibit the immune response against self-tissues

Which phase of acute inflammation is characterized by vasodilation and increased permeability?

  • Vascular phase (correct)
  • Cellular phase
  • Initial phase
  • Resolution phase

Why is matching Human Leukocyte Antigens (HLA) critical in transplantation?

  • To accelerate the healing process of the donor site
  • To decrease the likelihood of organ infection
  • To ensure the immune system identifies the graft as self (correct)
  • To enhance the function of the transplanted tissue

What is the main consequence of HLA mismatch in organ transplantation?

<p>Increased risk of alloreactive T-cell activation (C)</p> Signup and view all the answers

Which of the following statements about the cellular phase of acute inflammation is accurate?

<p>It includes the process of leukocyte attraction and phagocytosis (C)</p> Signup and view all the answers

What is the primary immunoglobulin involved in Type I hypersensitivity reactions?

<p>IgE (C)</p> Signup and view all the answers

Which of the following best describes Type II hypersensitivity?

<p>Antibody-mediated cytotoxic reactions (D)</p> Signup and view all the answers

In Type I hypersensitivity, which immune cells are activated by the interaction of allergens and IgE antibodies?

<p>Mast cells (D)</p> Signup and view all the answers

What is a key characteristic that distinguishes Type III hypersensitivity from other types?

<p>Formation of immune complexes (B)</p> Signup and view all the answers

Which of the following substances is released from mast cells during an allergic reaction in Type I hypersensitivity?

<p>All of the above (D)</p> Signup and view all the answers

What is the role of plasma cells in the immune response involved in Type I hypersensitivity?

<p>To produce IgE antibodies (D)</p> Signup and view all the answers

What type of immune response is characteristic of Type IV hypersensitivity?

<p>Delayed hypersensitivity reaction (B)</p> Signup and view all the answers

Which of the following reactions is classified under Type II hypersensitivity?

<p>Hemolytic anemia (B)</p> Signup and view all the answers

What is the primary mechanism through which Type IV Hypersensitivity causes tissue injury?

<p>T-cell mediated immune response (D)</p> Signup and view all the answers

Which type of hypersensitivity is primarily associated with the formation of immune complexes?

<p>Type III Hypersensitivity (B)</p> Signup and view all the answers

What triggers the initiation of allergic rhinitis in susceptible individuals?

<p>Exposure to specific airborne allergens (B)</p> Signup and view all the answers

What role do cytokines play in Type IV Hypersensitivity?

<p>They activate macrophages and cytotoxic T cells (A)</p> Signup and view all the answers

In rheumatoid arthritis, which component is mistakenly identified as a foreign antigen by the immune system?

<p>Components of the synovial membrane (B)</p> Signup and view all the answers

Which symptom is NOT typically associated with Type IV Hypersensitivity reactions such as contact dermatitis?

<p>Joint inflammation (D)</p> Signup and view all the answers

What is the end result of B-cell class switching in the context of allergic rhinitis?

<p>Increased production of IgE (B)</p> Signup and view all the answers

What is the typical time frame for the development of symptoms in Type IV Hypersensitivity reactions?

<p>After several days (A)</p> Signup and view all the answers

Which type of hypersensitivity reaction is associated with Contact Dermatitis?

<p>Type IV hypersensitivity (D)</p> Signup and view all the answers

What are the primary symptoms of food allergies in children?

<p>Hives, abdominal pain, and allergic rhinitis (D)</p> Signup and view all the answers

What role does IgE play in allergic reactions?

<p>It promotes the release of histamine and cytokines. (C)</p> Signup and view all the answers

How is a diagnosis of food allergies typically established?

<p>Through a multifaceted approach including food history and serum IgE testing. (D)</p> Signup and view all the answers

What is the major difference between systemic and local reactions in food allergies?

<p>Systemic reactions involve the cardiovascular system, while local reactions do not. (A)</p> Signup and view all the answers

Which of the following is NOT typically recognized as a common allergen for allergic rhinitis?

<p>Shellfish (C)</p> Signup and view all the answers

What processes are involved in the sensitization phase of contact dermatitis?

<p>Dendritic cells capturing haptens and stimulating T cell production. (D)</p> Signup and view all the answers

What symptom is most commonly associated with severe allergic rhinitis attacks?

<p>Sneezing (A)</p> Signup and view all the answers

What is a key characteristic of an erythematous rash associated with contact dermatitis?

<p>It typically involves the formation of papules and vesicles. (B)</p> Signup and view all the answers

During the vascular phase of acute inflammation, which response is observed first?

<p>Vasoconstriction. (D)</p> Signup and view all the answers

Which factor primarily drives the chemotaxis of leukocytes to the site of injury?

<p>Release of cytokines. (A)</p> Signup and view all the answers

What typically initiates the symptoms of contact dermatitis after exposure to an offending agent?

<p>A delayed hypersensitivity reaction. (B)</p> Signup and view all the answers

In the cellular phase of acute inflammation, what occurs after leukocyte margination?

<p>Transmigration through the vessel walls. (C)</p> Signup and view all the answers

What is the primary function of the inflammatory response during acute inflammation?

<p>To eliminate microorganisms and damaged tissue. (D)</p> Signup and view all the answers

What is a common treatment approach for severe cases of contact dermatitis?

<p>Use of systematic corticosteroids. (C)</p> Signup and view all the answers

Which process in phagocytosis involves the destruction of engulfed pathogens?

<p>Intracellular killing. (B)</p> Signup and view all the answers

Flashcards

Hypersensitivity

An abnormal immune response that leads to tissue damage. It's classified into four types based on the immune components involved.

Type I Hypersensitivity

A type of hypersensitivity triggered by IgE antibodies binding to mast cells and basophils, releasing histamine and other inflammatory mediators.

Type II Hypersensitivity

A type of hypersensitivity where IgG or IgM antibodies target antigens on cells, leading to their destruction.

Type III Hypersensitivity

A type of hypersensitivity caused by the formation of immune complexes (antibody-antigen complexes) that deposit in tissues and cause inflammatory damage.

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Type IV Hypersensitivity

A type of hypersensitivity mediated by sensitized T lymphocytes, which take time to develop and cause cell and tissue damage.

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Allergic Rhinitis

An upper respiratory tract disorder caused by a Type I allergic reaction to inhaled allergens, leading to symptoms like runny nose, sneezing, and watery eyes.

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Food Allergies

A type of allergic reaction triggered by the ingestion of specific food allergens, leading to various symptoms like hives, swelling, and difficulty breathing.

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Contact Dermatitis

A skin reaction caused by a Type IV hypersensitivity response to haptens, leading to itchy, red rashes.

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Acute Inflammation

An immediate, localized response to injury that involves vascular changes and the recruitment of immune cells to the site of injury.

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Vascular Phase of Inflammation

The initial phase of acute inflammation characterized by vasoconstriction followed by vasodilation, increased vascular permeability, and fluid leakage into the tissues.

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Cellular Phase of Inflammation

The phase of acute inflammation characterized by the migration of leukocytes, such as neutrophils and macrophages, from the bloodstream to the site of injury.

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Phagocytosis

The process by which leukocytes engulf and destroy harmful agents, such as bacteria, viruses, and cellular debris.

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Human Leukocyte Antigens (HLA)

Proteins expressed on the surface of cells that allow the immune system to distinguish self from nonself, playing a crucial role in organ transplantation compatibility.

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Graft Rejection

The immune system's rejection of transplanted organs due to differences in HLA between the donor and recipient.

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Mast Cell Degranulation

The process by which mast cells, activated by IgE antibodies, release histamine and other inflammatory mediators leading to an allergic reaction.

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Allergen

A substance that triggers IgE antibody production and subsequent mast cell degranulation, leading to allergic reactions.

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Mast Cell

A type of white blood cell involved in allergic reactions, which binds IgE and releases histamine upon activation.

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Basophil

A type of white blood cell that releases histamine, which is involved in allergic reactions.

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Histamine

A chemical mediator released by mast cells and basophils during allergic reactions, causing vasodilation, increased vascular permeability, and bronchoconstriction.

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Leukocyte

A type of white blood cell that plays a key role in the immune system's response to infection.

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Chemotaxis

The movement of leukocytes from the bloodstream to the site of injury, guided by chemical signals.

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Leukocyte Adhesion

The sticking of leukocytes to the inner lining of blood vessels, allowing them to migrate out of the blood and into the tissues.

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Leukocyte Transmigration

The process by which leukocytes squeeze through the blood vessel walls and enter the surrounding tissues.

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Leukocyte Margination

The process by which leukocytes adhere to the endothelium (inner lining of blood vessels) and then migrate to the site of injury.

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Neutrophil

A type of leukocyte that is the first responder to injury and infection, engulfing bacteria and other pathogens.

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Macrophage

A type of leukocyte that scavenges cellular debris and pathogens, playing a role in tissue repair and the immune response.

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Cytotoxic T Cell

A type of leukocyte that plays a role in the immune response by destroying infected cells and tumor cells.

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Helper T Cell

A type of T cell that releases cytokines and stimulates other immune cells, playing a role in inflammation and immune regulation.

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Cytokine

A type of protein molecule that acts as a messenger in the immune system, stimulating or inhibiting immune responses.

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Autoimmune Reaction

A type of immune reaction that occurs when the body's immune system mistakenly attacks its own tissues, leading to various autoimmune diseases.

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Rheumatoid Arthritis

A type of immune complex disease characterized by chronic inflammation of the joints, caused by autoantibodies targeting joint components.

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Type 1 Diabetes

A type of diabetes caused by the destruction of pancreatic beta cells, which produce insulin, by the body's own immune system.

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Elicitation Phase of Contact Dermatitis

An inflammatory skin reaction caused by the activation of memory T cells in response to the re-exposure to an allergen, often leading to localized itching, redness, and swelling.

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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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CS 4.1 Disorders of Immune Response 2024 PDF

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.

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