Introduction to Immunology

Introduction to Immunology

• Immunology is the study of the immune system and its response to foreign substances.
• It encompasses a wide range of topics, from the structure of immune cells to the mechanisms of immune responses.
• The immune system is a complex network of cells, tissues, and organs that work together to protect the body from pathogens.

Types of Immunity

• Innate immunity: The body's first line of defense against pathogens. It's non-specific and rapid.
  • Physical barriers (skin, mucous membranes)
  • Chemical barriers (enzymes, acids, antimicrobial peptides)
  • Cellular components (phagocytes, natural killer cells)
• Adaptive immunity: A more specific and tailored response to pathogens, developing after exposure.
  • Humoral immunity: Mediated by antibodies produced by B lymphocytes.
  • Cell-mediated immunity: Mediated by T lymphocytes, which directly attack infected cells.

Cells of the Immune System

• Lymphocytes: A crucial cell type in adaptive immunity.
  • B cells: Produce antibodies, marking pathogens for destruction.
  • T cells: Directly kill infected cells or activate other immune cells.
    • Helper T cells (CD4+): Coordinate the immune response.
    • Cytotoxic T cells (CD8+): Kill infected cells.
  • Natural killer (NK) cells: Part of innate immunity, recognize and destroy abnormal cells.
• Phagocytes: Cells that engulf and destroy pathogens.
  • Macrophages: Important antigen-presenting cells.
  • Neutrophils: Abundant, first responders to infection.
• Antigen-presenting cells (APCs): Display foreign antigens to T cells, initiating adaptive immunity.
  • Dendritic cells, macrophages, B cells.

Antigen-Antibody Interactions

• Antigens: Foreign molecules that trigger an immune response.
• Antibodies (Immunoglobulins): Specialized proteins produced by B cells that bind to specific antigens.
• Specificity: Antibodies are specific to particular antigens.
• Diversity: The immune system produces a vast array of antibodies to recognize a diverse range of antigens.

Immune Response Mechanisms

• Inflammation: A localized response to damage or infection, characterized by redness, swelling, heat, and pain.
• Complement system: A set of proteins that enhance the immune response, promoting pathogen destruction or inflammation.
• Cytokines: Signaling molecules that regulate the immune response, influencing cell activation.
• Memory cells: Upon exposure to an antigen, the immune system creates memory cells. These allow for a faster and stronger response upon subsequent exposures to the same antigen.

Immunological Disorders

• Autoimmune diseases: The immune system mistakenly attacks the body's own tissues.
• Immunodeficiency disorders: The immune system is weakened or deficient, leading to increased susceptibility to infections.
• Hypersensitivity reactions: Excessive or inappropriate immune responses to harmless substances, causing allergic reactions.

Vaccination

• Vaccination introduces a weakened or inactive form of a pathogen to stimulate an immune response and create memory cells.
• This protects the individual from subsequent exposure to the actual pathogen.
• Vaccination is crucial in preventing infectious diseases.

Immune System and Disease

• Infections: The immune system defends against invading pathogens like viruses, bacteria, and parasites.
• Cancer: The immune system can also identify and eliminate cancerous cells.
• Transplantation: Rejection of transplanted organs often results from an immune response against the foreign cells.

Immunological Techniques

• ELISA (enzyme-linked immunosorbent assay): A common laboratory technique used for detecting and quantifying antibodies or antigens.
• Flow cytometry: A technique used to identify and quantify different types of immune cells based on their surface markers.

This quiz covers the basics of immunology, focusing on the immune system's structure and its response to foreign substances. Topics include innate and adaptive immunity, as well as the various cells involved in the immune response. Test your knowledge on how the immune system protects the body from pathogens.