Immunology Lecture 1 PDF

Immunology Lecture 1 An overview of the immune system and immunity: Characteristics of immune response. - Innate and acquired immunity - Brief description of cells and organs of the immune system.  Fundamentals Immunology Host defense mechanisms Study of the genetic, biological...

Immunology Lecture 1 An overview of the immune system and immunity: Characteristics of immune response. - Innate and acquired immunity - Brief description of cells and organs of the immune system.  Fundamentals Immunology Host defense mechanisms Study of the genetic, biological, and physical characteristics of the immune system Ways in which the body protects itself from pathogens. Three lines of defense First two lines of defense are nonspecific. Third line of defense, the immune response: which is very specific. In the third line of defense, special proteins called antibodies are produced in response to foreign substances called antigens. Categories of Host Defense Mechanisms Innate non-specific Adaptive specific Immunity Immunity Big Picture: Immunity The Concept of Immunity Immunity: ability to ward off (fight off) disease Susceptibility: lack of resistance to a disease Innate immunity: defenses against any pathogen; rapid, present at birth (non-specific) Adaptive immunity: immunity or resistance to a specific pathogen; slower to respond, has memory component (specific) The Concept of Immunity Innate recognition Adaptive recognition mechanisms mechanisms Innate immunity Adaptive immunity Rapid (hours) Slow (days) Non-specific Highly specific Physical / Chemical Two branches: Barriers Humoral response Cellular defense Cellular response Neutrophils Basophiles Eosinophils Nonspecific Host Defense Mechanisms Innate immunity are general and serve to protect the body against many harmful substances. Other nonspecific host defense mechanisms: Mechanical & physical barriers to invasion Chemical factors Microbial antagonism Fever & the inflammatory response Phagocytic white blood cells The Concept of Immunity Toll-like receptors (TLRs) on host cells attach to pathogen-associated molecular patterns (PAMPs) Common PAMPs: Peptidoglycan, part of bacterial cell wall Flagellin, a protein found in bacterial flagella Lipopolysaccharide (LPS) in outer membrane of gram-ve bacteria Lipopeptides, molecules expressed by most bacteria Nucleic acids such as viral DNA or RNA TLRs bound to PAMPs induce the release of cytokines from the host cell that regulate the intensity and duration of immune responses The Concept of Immunity Transcription factors Activated Protein 1 Apoptosis Interferon Regulatory Factor Interferon Nuclear factor Kapa B Cytokines TLRs TLR detection First Line of Defense: Physical Factors Skin is an excellent physical barriers Dermis: inner portion made of connective tissue Epidermis: outer portion made of tightly packed epithelial cells containing keratin, a protective protein Shedding and dryness of skin inhibits microbial growth Top layers of epidermis with keratin Epidermis Dermis First Line of Defense: Physical Factors Mucous membranes Epithelial layer that lines the gastrointestinal, respiratory, and genitourinary tracts Mucus: viscous glycoproteins that trap microbes and prevent tracts from drying out Lacrimal apparatus: drains tears; washes eye Lacrimal glands Upper eyelid Lacrimal canal Nasolacrimal duct First Line of Defense: Physical Factors Ciliary escalator (Mucociliary) transports microbes trapped in mucus away from the lungs Earwax prevents microbes from entering the ear Urine cleans the urethra via flow Vaginal secretions move microbe out of the vagina Peristalsis, defecation, vomiting, diarrhea Trapped particles in mucus Cilia Goblet cells Ciliated cells Computer-enhanced First Line of Defense: Chemical Factors Sebum forms a protective film and lowers the pH (3–5) of skin Lysozyme in perspiration, tears, saliva, and urine destroys bacterial cell walls Low pH (1.2–3.0) of gastric juice destroys most bacteria and toxins Low pH (3–5) of vaginal secretions inhibit microbes Normal Microbiota and Innate Immunity Normal microbiota Commensalism: one organism benefits while the other (host) is unharmed Building up microbial flora since birth Many sources, mother, environment, etc Normal Microbiota and Innate Immunity Normal microbiota compete with pathogens via microbial antagonism Produce substances harmful to pathogens Alter conditions that affect pathogen survival Normal microbiota, prevent colonization of “new arrivals” as a result of competition for sites and nutrients and production of harmful substances to pathogens Probiotics: live microbial cultures administered to exert a beneficial effect Skin Microbiome Link https://youtu.be/MWE3U3FItlc  Types of Acquired Immunity Acquired immunity: immunity that results from the production or receipt of antibodies during life Immunity is always Acquired Immunity can be naturally acquired during your lifetime (Natural Immunity) or artificially induced into your system (Artificial Immunity) Immunity can be produced within the person him self (Active immunity) or produced & transferred from another person (Passive immunity) Types of Acquired Immunity Immunity Natural Acquired Artificial Acquired Active Passive Active Passive Naturally acquired active immunity Artificially acquired active immunity Naturally acquired passive immunity Artificially acquired passive immunity Naturally Acquired Immunity Naturally Acquired Active Immunity Immunity results when the person actively develop immunity within him self. Infections with bacteria and viruses are the best model to describe this type of immunity. Naturally Acquired Passive Immunity Immunity results when a person gets immunity from another person. Small antibodies such as IgG, found in mother’s blood can cross the placenta to reach the fetus and give him/her protection Artificially Acquired Immunity Artificially Acquired Active Immunity Immunity results when a person gets him/her immunity via an artificial form (e.g. receives a vaccine). Then the person body will Actively produce antibodies. A vaccine is defined as material that can artificially induce immunity to an infectious disease, usually following injection or ingestion of the vaccine. Most vaccines are made from living or dead pathogens or the toxins that they produce. Usually provides long-lasting protection Artificially Acquired Immunity Artificially Acquired Passive Immunity Immunity results when a person receives immunity from another person Antibodies are received that were produced by another person(s) or by an animal Usually provides only temporary protection Antibodies from an immune person are transferred to a susceptible person (e.g., hepatitis B immunoglobulin). Types of Adaptive Immunity Naturally Acquired Active Immunity Resulting from infection Naturally Acquired Passive Immunity Small antibodies, IgG, present in mother’s blood cross the placenta to reach the fetus Artificially Acquired Active Immunity Injection of vaccination (immunization) Artificially Acquired Passive Immunity Injection of antibodies