Introduction to Immunology

Pharmaceutical Microbiology II

• Course taught by Dr./Fahad Alzowahi, Assistant Professor in Microbiology, Pharmacy Department.

Brief History of Immunology

• The Latin term "immunis", meaning "exempt", is the origin of the English word "immunity".
• Immunity is the state of protection and defense from infectious diseases.
• Thucydides (430 BC) described a plague in Athens, noting that those who recovered were immune to subsequent infections.
• The Chinese and Turks developed early attempts at inducing immunity during the 15th century.

Smallpox Vaccination

• Reports suggest using dried smallpox pustules to induce future immunity.
• In 1798, Edward Jenner demonstrated smallpox vaccination.

Attenuated Vaccines

• Louis Pasteur (1884) developed attenuated vaccines reducing disease intensity.

Phagocytosis

• Elie Metchnikoff (1884) observed bacteria being engulfed and destroyed by cells, a process called phagocytosis.

Antibody Discovery

• George Nuttall (1888) identified the presence of antibodies within serum.
• Emil von Behring and Shibasaburo Kitasato (1890) demonstrated antibody activity against diphtheria and tetanus toxins, marking the start of the humoral theory of immunity.

Nobel Prizes in Immunology

• The table outlines Nobel Prize winners and their associated immunological concepts.

Immunology Definition

• Immunology is the branch of biomedical science studying the body's defense reactions (immunity).
• Immunity is the host's defense mechanism against foreign bodies (e.g., bacteria, viruses, fungi, parasites).
• The immune response is the body's reaction to foreign bodies or pathogens.

Immune System Components

• The immune system is a complex network of cells, tissues, and organs working together to defend the body against pathogens.
• Central (primary lymphoid) organs: Bone marrow and Thymus gland. They are responsible for the production and maturation of lymphocytes.
• Peripheral (secondary lymphoid) organs: Lymph nodes, Spleen, Tonsils, Vermiform appendix, Peyer's patches. These are sites for further lymphocyte maturation and trapping of antigens for exposure to T and B cells.

Types of Immunity

• Immunity can be innate (natural) or acquired (adaptive).
• Innate immunity is present from fetal development and is not specific to prior exposure. It acts non-specifically against all invaders.
• Innate immunity has four types of defense barriers:
• Anatomical and physical barriers—skin, tracheal cilia, digestive tract peristalsis, hairs in the nose.
• Physiological and chemical barriers—sweat, sebum, earwax, enzymes (lysozyme, phospholipase), gastric acid, defensins.
• Phagocytic (cellular) barriers—neutrophils, eosinophils, basophils, natural killer (NK) cells and macrophages.
• Inflammatory barriers—inflammation response.
• Acquired immunity develops in response to prior exposure; it is specific to the targeted pathogen.

Phagocytosis Process

• This is a process where cells engulf and destroy microbes.
• The steps include attachment, ingestion, fusion with lysosomes, digestion, and release of waste products.

Inflammatory Barriers

• Inflammation is an innate immune defense against injury, infection, or allergy.
• Inflammation's function is to protect the body from foreign invaders and repair tissue damage.
• Inflammation is characterized by cardinal signs: pain, swelling (tumor), redness (rubor), heat (calor), and loss of function.
• Inflammation involves vasodilation, increased capillary permeability, and leukocyte migration to the damaged tissue.

Factors Affecting Innate Immunity

• Age, race, environmental conditions, nutrition, and genetic factors influence innate immunity. 

Immune System Advantages and Disadvantages

• Advantages of inflammation include destroying pathogens, preventing further injury, and promoting tissue repair.
• Disadvantages of inflammation include pain, organ rupture, tissue adhesion, and chronic diseases.