Lecture_28_Immune_System 2.pptx

GENERAL BIOLOGY II Lecture 28: Animal Immune Systems Chapter: 41 The Animal Immune System The Animal Immune System Pathogens – Agents that cause infectious disease, such as bacteria, viruses, fungi, protists, worms, and other parasites The Animal Immune System Immune system can determine self from n...

GENERAL BIOLOGY II Lecture 28: Animal Immune Systems Chapter: 41 The Animal Immune System The Animal Immune System Pathogens – Agents that cause infectious disease, such as bacteria, viruses, fungi, protists, worms, and other parasites The Animal Immune System Immune system can determine self from nonself The Animal Immune System Autoimmune diseases – result from the immune system attacking an animal’s own cells as if they are a pathogen Immunodeficiency – results from the immune system not recognizing pathogens as notself The Animal Immune System The immune system provides two forms of immunity: Innate Immunity Adaptive Immunity The Animal Immune System The immune system provides two forms of immunity: Innate Immunity – provides protection against all forms of infection in a non-specific manner; does not depend on previous exposure Adaptive Immunity – specific to a given pathogen; results from exposure to that specific pathogen Innate Immune System Physical and Chemical Barriers  Skin  Skin microbiome  Mucus membranes / secretions / tears Innate Immune System Physical and Chemical Barriers  Skin  Skin microbiome  Mucus membranes / secretions / tears Inflammatory Response - employs neutrophils and macrophages to surround and kill invading pathogens  Symptoms of IR: Redness, heat, swelling, pain Innate Immune System Physical and Chemical Barriers Inflammatory Response - employs neutrophils and macrophages to surround and kill invading pathogens Histamine – a chemical mediator released by damaged tissue cells and mast cells which cause the capillaries to dilate and become more permeable Innate Immune System Physical and Chemical Barriers Inflammatory Response  Excess fluid from leaky capillaries cause swelling (which presses on nerves) and pain  These conditions summon white blood cells to the region Innate Immune System Physical and Chemical Barriers Inflammatory Response  Neutrophils are the first WBCs to arrive, and they phagocytize (eat) debris, dead cells, and bacteria  If neutrophils are overwhelmed, they release Cytokines Innate Immune System Physical and Chemical Barriers Inflammatory Response  Cytokines – proteins that attract more WBCs, including monocytes  Monocytes are longer-lived cells that become Macrophages  Macrophages are more powerful phagocytes than neutrophils Innate Immune System Physical and Chemical Barriers Inflammatory Response  Complement system – composed by a number of blood plasma proteins that increase the immune response of one or more specific immune responses Innate Immune System Physical and Chemical Barriers Inflammatory Response  Complement proteins can:  Trigger mast cells to release histamine  Attract phagocytes to a specific location  Bind directly to bacteria can cause them to burst Innate Immune System Physical and Chemical Barriers Inflammatory Response Virus-specific Response  Interferons – proteins produced by virus-infected cells that cause uninfected cells to prepare for viral infection by producing substances that interfere with viral replication Adaptive Immune System Adaptive Immune System Antigen – a large protein structure that the immune system recognizes as a foreign body Fragments of: Bacteria Viruses Molds Parasitic worms Adaptive Immune System Adaptive defenses primarily depend on B and T cells (B and T lymphocytes) Adaptive Immune System Adaptive defenses primarily depend on B and T cells (B and T lymphocytes) Each lymphocyte has a single kind of receptor to combine with a specific antigen (like a lock and key) Adaptive Immune System Adaptive Immunity Pathways Cell-mediated immunity Antibody-mediated (humoral) immunity Adaptive Immune System Cell-mediated immunity – T-cells target and destroy any cells that present a specific antigen Adaptive Immune System Cell-mediated immunity – T-cells target and destroy any cells that present a specific antigen  Helper T cells may come into contact with an antigen and release cytokines to call Cytotoxic T cells to the area Adaptive Immune System Cell-mediated immunity – T-cells target and destroy any cells that present a specific antigen  Helper T cells may come into contact with an antigen and release cytokines to call Cytotoxic T cells to the area  Cytotoxic T cells either phagocytize or trigger apoptosis in infected cells Chapter 7.3: Adaptive Immune Defenses Adaptive Immune System Adaptive Immunity Pathways Cell-mediated immunity Antibody-mediated (humoral) immunity Adaptive Immune System Antibody-mediated (humoral) immunity  An antigen binds with a B cell’s receptor Adaptive Immune System Antibody-mediated (humoral) immunity  An antigen binds with a B cell’s receptor  The B cell then undergoes rapid clonal expansion, creating B memory cells, and plasma cells  The plasma cells created secrete antibodies for the original antigen Chapter 7.3: Adaptive Immune Defenses Adaptive Immune System Antibody-mediated (humoral) immunity  Only the B cells that have receptors that fit the antigen undergo clonal expansion  Most cloned B cells become plasma cells, which circulate in the blood and lymph and constantly excrete antibodies keyed to the original antigen Adaptive Immune System Antibody-mediated (humoral) immunity  A minority of the cloned B cells become B memory cells, which have a long life and have the same receptors  Once the infection has passed, any remaining plasma cells undergo apoptosis (programmed cell death) Adaptive Immune System Antibody Structure  Y – shaped with two antigen binding sites Adaptive Immune System Antibody Function  Many antibodies will bind with the antigens, covering the offending molecule so that it can’t bind  Antibodies then call for other white blood cells Adaptive Immune System Antibody Classes  IgG - Enhances phagocytosis by WBCs  IgM - Activates compliment and clumps cells  IgA - Prevents pathogens from attaching to epithelial cells in the digestive and respiratory tracts  IgD - Signifies readiness of B cells  IgE - Responsible for immediate allergic response and protection against certain parasitic worms Adaptive Immune System Cytotoxic T cells – specialized T lymphocytes with storage vacuoles that contain perforins and storage vacuoles that contain granzymes (an enzyme that causes apoptosis) Chapter 7.3: Adaptive Immune Defenses Adaptive Immune System Helper T cells – specialized T lymphocytes that regulate immunity by secreting cytokines  B lymphocytes cannot be activated without T cell help  HIV (which causes AIDS) attacks T cells, which leaves patients vulnerable to opportunistic infections, which may eventually cause death Adaptive Immune System Memory T cells – remain within the body and can jump-start an immune response to an antigen previously present in the body Acquired Immunity Immunization – involves the use of vaccines to expose the immune system to the antigen Vaccine – substances that contain an antigen to which the immune system responds Acquired Immunity Active immunity – Vaccines Vaccines have traditionally been composed of either the pathogen itself or their products that have been treated to no longer be virulent (able to cause the disease) Today, we can use genetic engineering to make bacteria mass produce a protein from the pathogen to make a vaccine (Hep B and Malaria) Acquired Immunity Active immunity – Vaccines Initially, vaccines typically illicit an immune response that peaks around 14 days after injection A second dose of vaccine (Booster) will typically illicit a much faster and higher concentration of antibodies, because memory B and T lymphocytes are already present Chapter 7.4: Acquired Immunity The Animal Immune System Exam 4 on Friday 4:00 PM omplete the Quiz Last name begins with go to A - F Pappert Lecture Hall, Bayer Learning Center G - O Laura Falk Lecture Hall, Mellon Hall P - Z Maurice Falk Lecture Hall, Mellon Hall on Launchpad Read The rest of Chapter 41: The Immune System