Veterinary Immunology: Innate and Adaptive Immunity Notes

Innate and Adaptive Immunity

  • Definition:

    • Innate Immunity:

      • Present at birth;

      • Fast-acting;

      • Non-specific;

      • First line of defense;

      • No memory of previous assaults.

    • Adaptive Immunity:

      • Develops over time;

      • Slow-acting;

      • Specific recognition of antigens;

      • Memory of previous exposure to pathogens.

Importance of the Immune System

  • Protection Against Pathogens:

    • Safeguards humans and animals from invading pathogens such as bacteria, viruses, fungi, and parasites.

    • Involves recognition, response, and elimination of health threats and pathogens.

  • Functions of Immunity:

    • Detecting pathogens;

    • Inflammatory processes (e.g., antibody production, cellular immunity, phagocytosis);

    • Tissue repair;

    • Preventing infection and controlling morbidity and mortality.

Barriers of the Innate Immune System

  • Four immunological barriers:

    1. Physical Barriers:

    • Epithelial barriers: Skin and mucosa (e.g. respiratory tract, gastrointestinal tract).

    1. Physiological Barriers:

    • Involves temperature (e.g. fever), pH (e.g. acidity of stomach), and chemical mediators such as enzymes and peptides.

    1. Phagocytic Barriers:

    • Phagocytes engulf pathogens via phagocytosis.

    1. Inflammatory Barriers:

    • Signs of inflammation include heat, redness, pain, and swelling; promotes tissue healing.

Key Components of the Immune System

  • Organs:

    • Bone marrow, thymus, lymph nodes, spleen.

  • Immune Cells:

    • Macrophages, neutrophils, lymphocytes, natural killer (NK) cells, eosinophils.

  • Proteins & Molecules:

    • Antibodies, cytokines, complements, major histocompatibility complex (MHC) molecules.

Adaptive Immunity

  • Characteristics:

    • Specificity to antigens;

    • Rapid amplification of response after exposure;

    • Development of immunological memory for quicker responses;

    • Provides ongoing protection, often lifelong.

Clinical Relevance in Veterinary Science

  • Colostral Immunity:

    • Critical for neonatal domestic livestock (provides essential nutrients and antibodies).

  • Resistance to Infection:

    • Importance of developing immunity to ensure optimal health and productivity.

  • Disease Diagnosis:

    • Identifying immune disorders for early detection and intervention.

  • Vaccinations:

    • Essential for protecting populations from infectious diseases and maintaining herd health.

Mechanisms of Immune Response

  • Innate Mechanisms:

    • Immediate response to pathogens;

    • Attraction of immune cells to the site of infection;

    • Engagement of humoral factors (like antibodies).

  • Adaptive Mechanisms:

    • Engagement of T and B lymphocytes;

    • Activation of memory cells for rapid and potent responses upon re-exposure to pathogens.