Autoimmunity ppt

Mid-Semester Exam Details

  • Date: Tuesday, March 18th, 2025

  • Format: In-person

  • Location: Highfield Campus (see timetable for specific room and time)

  • Exam Structure: 40 questions covering innate and adaptive immunity

  • Special Consideration: Extra time available for eligible students via student office

  • Instructions: Students must remain seated if they finish early.

Autoimmune Diseases

  • Common Autoimmune Diseases:

    • Multiple sclerosis

    • Systemic Lupus Erythematosus

    • Rheumatoid arthritis

Learning Objectives

  • Breakdown of immune system functioning leading to autoimmune diseases.

  • Plasticity of the immune system regarding pathogen recognition and its consequences.

  • Key Points:

    • Effectors of acquired immunity: antibodies, T-cells

    • Antigen presentation by professional antigen-presenting cells (APCs)

    • Mechanisms of tolerance.

Prevalence of Autoimmune Diseases

  • Statistics (2018 data):

    • Approximately 4 million cases in the UK

    • 1 in 5 individuals affected

    • 75% of cases occur in women.

  • Autoimmune diseases rank as the 4th largest cause of disability among women.

  • Rheumatoid Arthritis affects approximately 1 in 100 individuals.

Mechanism of Antigen Presentation

  • Steps of Pathogen Recognition by APCs:

    1. APC recognizes a pathogen.

    2. Internalization and antigen processing.

    3. Peptide presented via MHC class II.

    4. Interaction of TCR complex with the peptide.

    5. Danger signal and co-stimulation.

    6. T cell proliferation and cytokine response.

    7. Activation of B cells and CD8 T cells to launch a full immune response.

  • Normal CD4 T cell response: involves MHC-antigen and co-stimulation interactions.

Causes of Autoimmunity

  • The immune system typically distinguishes between self and non-self.

  • Autoimmune diseases arise when:

    • Control processes are interrupted, leading to lymphocyte suppression failure.

    • Cells/tissues are altered and mistaken for non-self.

  • Factors that may trigger autoimmune processes include:

    • Bacteria, viruses, toxins, and certain drugs.

    • Genetic predisposition to autoimmune disorders.

Tolerance in the Immune System

  • Tolerance: The immune system's ability to avoid attacking self-antigens.

  • Breakdown of tolerance leads to autoimmune disease.

    • Tolerance mechanisms include:

      • Central tolerance (during T cell maturation in the thymus).

      • Peripheral tolerance (involving signals from normal cellular tissue).

Role of MHC Molecules

  • MHC molecules are critical antigen-presenting structures.

  • They partly determine immune responses to antigens and are implicated in susceptibility and development of autoimmune diseases.

Key Discoveries in Immunology

  • Peter C. Doherty and Rolf M. Zinkernagel won the Nobel Prize in 1996 for discoveries related to specificity in cell-mediated immune defense.

Cytotoxic T Cells vs. B Cells

  • Only viral infected cells are eliminated by cytotoxic T cells, not free virus or antigen.

  • Key differences exist in responses between T cells and B cells.

T Cell Development and Selection

  • T cells develop in the thymus with processes of:

    • Central Tolerance: Reactive T cells against self are eliminated; involves positive and negative selection.

    • Peripheral Tolerance: T cells in circulation depend on signals from normal tissues to survive; failure results in autoimmunity.

Figure Notes on T Cell Development

  • Various stages of T cell development (e.g., precursor, immature thymocyte) illustrate gene rearrangement and selection processes.

B Cell Development and Tolerance

  • Negative selection for B cells occurs in the bone marrow; cross-linking of IgM can lead to apoptosis of self-reactive B cells.

  • Immature B cells undergo receptor editing or deletion if they strongly react to self-antigens.

Conclusion of Autoimmune Processes

  • Chronic activation through inappropriate immune responses can lead to detrimental effects on the body, necessitating therapeutic interventions.

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