Podcast
Questions and Answers
Which of the following conditions is primarily characterized by autoantibodies against acetylcholine receptors?
Which of the following conditions is primarily characterized by autoantibodies against acetylcholine receptors?
What type of hypersensitivity is associated with Graves Disease?
What type of hypersensitivity is associated with Graves Disease?
The predominant autoantibody associated with systemic lupus erythematosus (SLE) targets which of the following?
The predominant autoantibody associated with systemic lupus erythematosus (SLE) targets which of the following?
Which autoimmune condition is characterized by antibodies against modified self antigens on platelets?
Which autoimmune condition is characterized by antibodies against modified self antigens on platelets?
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What type of drugs are primarily used in the treatment of autoimmune diseases to alter immune cell communication?
What type of drugs are primarily used in the treatment of autoimmune diseases to alter immune cell communication?
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Which statement accurately differentiates autoimmunity from autoimmune disease?
Which statement accurately differentiates autoimmunity from autoimmune disease?
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What is a key environmental factor that may influence the development of autoimmune diseases?
What is a key environmental factor that may influence the development of autoimmune diseases?
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In the context of immunological tolerance, what is oral tolerance?
In the context of immunological tolerance, what is oral tolerance?
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What does HLA-B27 predominantly associate with?
What does HLA-B27 predominantly associate with?
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Which mechanism primarily contributes to antibody-mediated autoimmune diseases?
Which mechanism primarily contributes to antibody-mediated autoimmune diseases?
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What role do regulatory T cells (Tregs) play in maintaining immune privilege?
What role do regulatory T cells (Tregs) play in maintaining immune privilege?
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What is the primary consequence of molecular mimicry in autoimmunity?
What is the primary consequence of molecular mimicry in autoimmunity?
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Which type of hypersensitivity is characterized by the formation of immune complexes?
Which type of hypersensitivity is characterized by the formation of immune complexes?
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Which of the following is NOT a characteristic of immunologically privileged sites?
Which of the following is NOT a characteristic of immunologically privileged sites?
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Which of these locations is considered an immunologically privileged site?
Which of these locations is considered an immunologically privileged site?
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What molecular mechanism contributes to autoimmune reactions seen in rheumatic heart disease?
What molecular mechanism contributes to autoimmune reactions seen in rheumatic heart disease?
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Which statement best describes molecular mimicry?
Which statement best describes molecular mimicry?
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Which of the following diseases is classified under antibody-mediated autoimmune diseases?
Which of the following diseases is classified under antibody-mediated autoimmune diseases?
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Which factor is known to play a role in immune tolerance within immunologically privileged sites?
Which factor is known to play a role in immune tolerance within immunologically privileged sites?
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Immunologically privileged tissues can release antigens into circulation. What is the consequence of this?
Immunologically privileged tissues can release antigens into circulation. What is the consequence of this?
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Which autoimmune condition is associated with type II hypersensitivity?
Which autoimmune condition is associated with type II hypersensitivity?
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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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Description
This quiz explores concepts of autoimmunity and autoimmune diseases, focusing on the differentiation between the two. You will learn about the genetic and environmental factors contributing to these diseases as well as the immunological mechanisms involved. Additionally, the quiz covers the classification of autoimmune diseases and potential immunotherapies for their treatment.
