Week 1 S - Intro to Immunology

Immunology Introduction

  • Importance of studying immunology:
    • Understanding defense mechanisms against pathogens.
    • Link to previous topics studied (e.g., innate vs adaptive immunity).
  • Topics Covered:
    • Innate versus Adaptive Immunity:
    • Innate: Immediate response, non-specific.
    • Adaptive: Delayed response, specific, improves upon re-exposure.
    • Antigens: Concept of self vs non-self.
    • Role of immune cells, organs, antibodies, cytokines.
    • Mechanisms underlying adaptive immunity.
    • Disorders of the immune system and relevance in vaccine development and immunodiagnostics.

Cells of the Immune System

  • Types of Immune Cells:
    • B cells: Produce antibodies for humoral immunity.
    • T cells: Involved in cellular immunity, include CD4+ and CD8+ T cells.
    • Macrophages and Neutrophils: Phagocytize pathogens and debris.
    • Dendritic Cells: Important for antigen presentation.
    • Natural Killer Cells: Attack virally infected and tumor cells.

Immune Responses

Innate Immunity
  • Rapid response (hours), non-specific.
  • Characteristics:
    • Same response rate regardless of pathogen repeat exposure.
    • Effective in neutralizing pathogens but may not always succeed.
  • Components: Physical barriers (skin, mucous membranes), inflammatory response.
Adaptive Immunity
  • Slower to develop (days), highly specific response.
  • Consists of:
    • Humoral Immunity: Mediated by antibodies from B cells.
    • Cell-Mediated Immunity: Involves T cells targeting abnormal cells (e.g., infected or cancerous).
  • Responds faster upon subsequent exposure due to memory cells.

Antibodies and their Functions

  • Types of Immunoglobulins:
    • IgG: Major antibody in blood, fights against infections.
    • IgA: Found in secretions (e.g., saliva, tears), protects mucous membranes.
    • IgM: First antibody produced, important in initial immune response.
    • IgE: Associated with allergic reactions.
    • IgD: Functions primarily as a receptor on B cells.

Vaccination and Immune Response

  • Vaccination's Importance:
    • Key public health measure; decreases mortality from infectious diseases.
  • Notable historical figure:
    • Edward Jenner: Developed smallpox vaccine from cowpox, establishing the principle of vaccination.
    • Significance: Initiated mass vaccination leading to the eventual eradication of smallpox.

Immune Disorders

  • Hypersensitivity: Exaggerated immune response leading to allergic reactions.
  • Autoimmunity: Immune response against self-antigens causing tissue damage.
  • Immunodeficiency: Conditions where immune response is reduced, e.g., SCID.
  • Acquired Immunodeficiency Syndrome (AIDS): Results from infection with HIV, severely affecting T cell function.

Cell Signaling and Immune Activation

  • Cell Signaling Pathways:
    • Involved in T cell activation and differentiation (notably through TCR and MHC interactions).
  • Cytokines: Signaling molecules that mediate and regulate immunity, inflammation, and hematopoiesis.

Conclusion

  • The interplay between innate and adaptive immunity is crucial for effective immune responses.
  • Immunological memory allows for quicker and more effective responses upon re-exposure to pathogens.
  • Self-tolerance: Vital for preventing reactions against the body's own tissues, can distinguish 'self' from 'non-self'.