Autoimmunity & Autoimmune Diseases Quiz

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Questions and Answers

Which of the following conditions is primarily characterized by autoantibodies against acetylcholine receptors?

  • Goodpasture’s Syndrome
  • Myasthenia Gravis (correct)
  • Graves Disease
  • Systemic Lupus Erythematous

What type of hypersensitivity is associated with Graves Disease?

  • Type II Hypersensitivity (correct)
  • Type III Hypersensitivity
  • Type IV Hypersensitivity
  • Type I Hypersensitivity

The predominant autoantibody associated with systemic lupus erythematosus (SLE) targets which of the following?

  • Acetylcholine receptor
  • Double-Stranded DNA (correct)
  • Basement membrane
  • Thyroid stimulating hormone receptor

Which autoimmune condition is characterized by antibodies against modified self antigens on platelets?

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

What type of drugs are primarily used in the treatment of autoimmune diseases to alter immune cell communication?

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

Which statement accurately differentiates autoimmunity from autoimmune disease?

<p>Autoimmune disease is a consequence of autoimmunity. (D)</p> Signup and view all the answers

What is a key environmental factor that may influence the development of autoimmune diseases?

<p>Exposure to certain infections (C)</p> Signup and view all the answers

In the context of immunological tolerance, what is oral tolerance?

<p>Desensitization to self-antigens through gastrointestinal exposure (C)</p> Signup and view all the answers

What does HLA-B27 predominantly associate with?

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

Which mechanism primarily contributes to antibody-mediated autoimmune diseases?

<p>Activation of complement through target cell lysis (C)</p> Signup and view all the answers

What role do regulatory T cells (Tregs) play in maintaining immune privilege?

<p>They suppress immune responses that could damage self-tissues. (D)</p> Signup and view all the answers

What is the primary consequence of molecular mimicry in autoimmunity?

<p>Self-tolerance breakdown leading to autoimmune disease (D)</p> Signup and view all the answers

Which type of hypersensitivity is characterized by the formation of immune complexes?

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

Which of the following is NOT a characteristic of immunologically privileged sites?

<p>High levels of immune cell infiltration (D)</p> Signup and view all the answers

Which of these locations is considered an immunologically privileged site?

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

What molecular mechanism contributes to autoimmune reactions seen in rheumatic heart disease?

<p>Cross-reactivity of antibodies formed against Streptococcus pyogenes (D)</p> Signup and view all the answers

Which statement best describes molecular mimicry?

<p>The presence of similar antigens leading to cross-reactivity (A)</p> Signup and view all the answers

Which of the following diseases is classified under antibody-mediated autoimmune diseases?

<p>Autoimmune Hemolytic Anemia (D)</p> Signup and view all the answers

Which factor is known to play a role in immune tolerance within immunologically privileged sites?

<p>Production of TGF-β (D)</p> Signup and view all the answers

Immunologically privileged tissues can release antigens into circulation. What is the consequence of this?

<p>Potential triggering of an immune response (A)</p> Signup and view all the answers

Which autoimmune condition is associated with type II hypersensitivity?

<p>Graves' Disease (B)</p> Signup and view all the answers

Flashcards

Immuno-privileged sites

Areas in the body where immune responses are normally suppressed.

Immunosuppressive factors

Substances that actively reduce immune responses.

Molecular mimicry

Antibodies attacking self-tissues because of similarities to antigens.

Rheumatic heart disease

Autoimmune disease where antibodies target heart valves after infections.

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Autoimmune hemolytic anemia

Autoimmune disease affecting red blood cells.

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CD4 T-cell

A type of white blood cell crucial for initiating and regulating immune responses.

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IFN-g

A type of cytokine that acts as an immune messenger.

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Antigen

A substance that triggers an immune response.

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Autoimmune Thrombocytopenia

A disorder where the immune system attacks platelets, causing low platelet count and increased bleeding risk.

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Goodpasture's Syndrome

An autoimmune disease affecting the basement membranes of the lungs and kidneys, leading to inflammation and potential organ damage.

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Myasthenia Gravis

An autoimmune disease affecting the acetylcholine receptors at the neuromuscular junction, leading to muscle weakness and fatigue.

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Graves' Disease

An autoimmune disorder affecting the thyroid gland, causing hyperthyroidism due to antibodies mimicking the action of TSH and stimulating the thyroid.

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Systemic Lupus Erythematosus (SLE)

A chronic autoimmune disease where the immune system attacks various parts of the body, forming complexes that cause inflammation and tissue damage.

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Autoimmunity

The immune system attacking the body's own tissues.

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Autoimmune disease

A condition where the immune system attacks the body's own tissues, causing damage and disease.

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What are some factors that may cause autoimmune diseases?

Both genetic predisposition and environmental factors can contribute to autoimmune diseases. Genetic factors may include specific gene variations like HLA-B27, while environmental factors could involve infections or exposure to certain toxins.

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What are some ways the immune system can cause autoimmune diseases?

Autoimmune diseases can arise due to various immune mechanisms such as: * Type II hypersensitivity: Antibodies targeting cell surface antigens, causing cell destruction. * Type III hypersensitivity: Immune complexes depositing in tissues leading to inflammation. * Type IV hypersensitivity: T cell-mediated inflammation targeting specific tissues.

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What is Oral Tolerance?

Oral tolerance means the immune system learns to ignore harmless antigens ingested through the mouth. It's a critical mechanism for preventing autoimmune reactions against food or gut bacteria.

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What is Immune Privilege?

Certain body sites like the brain, eyes and testes are considered immune privileged. This means they have mechanisms to limit immune responses, protecting them from inflammation.

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What is Immunosuppression?

Immunosuppression refers to reducing or suppressing the immune system's activity. This is often done using medications to prevent reactions like rejection of transplanted organs or to manage autoimmune diseases.

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What is HLA- B27?

HLA-B27 is a specific gene associated with an increased risk of developing ankylosing spondylitis (AS), a type of inflammatory arthritis that primarily affects the spine.

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Study Notes

Autoimmunity & Autoimmune Diseases

  • Autoimmunity is immune reactions against self (auto)antigens. These are typically benign.
  • Immune control mechanisms prevent the development of pathogenic autoimmunity.
  • Autoimmune diseases occur when mechanisms maintaining immunological tolerance to self-antigens break down.

Learning Objectives

  • Differentiate autoimmunity from autoimmune disease.
  • Describe genetic and/or environmental factors that may underlie the development of autoimmune diseases.
  • Describe potential immunological mechanisms that may cause autoimmune diseases.
  • Categorize autoimmune diseases according to their immunopathology (Type II, Type III, Type IV hypersensitivity).
  • Discuss immunotherapies for the treatment of autoimmune diseases (specific antibodies, cytokines, anti-cytokines, and anti-inflammatory agents).

Autoimmunity versus Autoimmune Diseases

  • Autoimmunity: Immune reactions against self (auto)antigens, generally benign.
  • Autoimmune diseases: Breakdown in one or more mechanisms that maintain immunological tolerance to self-antigens.

Immunological Tolerance to Self Antigens

  • Central tolerance: Generative lymphoid organs (thymus, bone marrow) eliminate self-reactive lymphocytes.
  • Peripheral tolerance: Peripheral tissues regulate self-reactive lymphocytes through apoptosis, anergy, or suppression.

Criteria for Defining a Disease as Autoimmune

  • Direct proof: Reproducing the disease by transferring antibodies (transplacental) or autoreactive T-cells.
  • Indirect proof: Recreation of the disease in animal models (spontaneous or experimental).
  • Circumstantial proof: Clinical clues (e.g., MHC associations, family history), improvement with immunosuppressive drugs.

Most Autoimmune Diseases Are Multifactorial

  • Genetic factors: Mendelian disorders (rare), family clustering, polygenic. HLA/MHC genes may contribute to disease development and progression.
  • Environmental factors: Certain drugs, modified environmental antigens (e.g., gluten), trauma, microbial antigens.

Gender & Hormones in Autoimmune Diseases

  • Females are more likely to develop autoimmune diseases than males.
  • Some autoimmune diseases worsen during pregnancy, while others improve. (Example: RA improves, SLE worsens)

HLA Associations with Autoimmune Diseases

  • Specific HLA alleles are associated with increased risk of certain autoimmune diseases. (e.g., HLA-B27 and ankylosing spondylitis).
  • Relative Risk (RR) calculations are used to assess disease risk with different HLA types.

Potential Triggers/Development Mechanisms of Autoimmune Diseases

  • Failure of oral tolerance
  • Release of sequestered antigens from immune privileged sites
  • Molecular mimicry
  • Polyclonal B-cell activation

Breakdown of Self Tolerance

  • Molecular Mimicry: Microbial antigens with epitopes mimicking self-antigens can trigger an immune response.
  • T-cells respond to microbial antigens which can cross-react with self-antigens
  • B-cells produce autoantibodies.

Autoimmune Diseases that are Antibody-Mediated

  • Autoimmune diseases are categorized as Type II (Type II hypersensitivity) and/or Type III (Type III hypersensitivity).
  • Examples include autoimmune hemolytic anemia, autoimmune thrombocytopenia, Goodpasture's syndrome.
  • Other examples include Myasthenia Gravis, Graves' Disease, and Systemic Lupus Erythematosus.
  • Immune complexes can be formed from antibodies and antigens which leads to inflammation.

Autoimmune Diseases, Type II Hypersensitivity

  • Myasthenia gravis
  • Graves' disease (antibodies target TSH receptors)
  • Autoimmune hemolytic anemia (antibodies target RBC)
  • Autoimmune thrombocytopenia (antibodies target platelets)

Autoimmune Diseases, Type III Hypersensitivity

  • Systemic lupus erythematosus

Autoimmune Diseases that are mainly T-Cell Mediated

  • Hashimoto's thyroiditis
  • Rheumatoid Arthritis
  • Multiple sclerosis
  • Type I Diabetes

Rheumatoid Arthritis

  • Chronic inflammation, erosion of synovium and bone
  • Immune infiltrate (T-cells, macrophages, B-cells, plasma cells)
  • Immune complexes (rheumatoid factor)
  • Genetic component, HLA-DRB1*04 alleles associated with risk and progression
  • Age of onset typically around 40–60
  • Treatment includes NSAIDs, immunosuppressants, biologics (e.g., anti-TNF-α)

Type 1 Diabetes

  • Destruction of insulin-producing beta cells of the pancreas by T-cells.
  • Genetic component: HLA-DQB1*02:01 and 03:01 alleles
  • Treatment: Insulin

Treatment of Autoimmune Diseases

  • Corticosteroids, immunosuppressants, biologics
  • Types of therapies include NSAIDs, immunotherapies.
  • Biological response modifiers and targeted immune modulators

Video Summary

  • A video overview of Autoimmunity, autoimmunity, and treatment of autoimmune diseases produced by the American Autoimmune Related Diseases Association.

Tolerance

  • Central Tolerance: T and B cells that react to self-antigens in the thymus and bone marrow are removed to prevent autoimmune responses.
  • Peripheral Tolerance: T and B cells that react to self-antigens are deactivated or removed in peripheral tissues.

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