* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 18 Defense Mechanisms of the Body
Survey
Document related concepts
Immunocontraception wikipedia , lookup
Human leukocyte antigen wikipedia , lookup
Lymphopoiesis wikipedia , lookup
Major histocompatibility complex wikipedia , lookup
DNA vaccination wikipedia , lookup
Complement system wikipedia , lookup
Monoclonal antibody wikipedia , lookup
Hygiene hypothesis wikipedia , lookup
Sjögren syndrome wikipedia , lookup
Immune system wikipedia , lookup
Molecular mimicry wikipedia , lookup
Adoptive cell transfer wikipedia , lookup
Adaptive immune system wikipedia , lookup
Polyclonal B cell response wikipedia , lookup
Cancer immunotherapy wikipedia , lookup
Immunosuppressive drug wikipedia , lookup
Transcript
Chapter 18 Lecture Outline* The Immune System Eric P. Widmaier Boston University Hershel Raff Medical College of Wisconsin Kevin T. Strang University of Wisconsin - Madison *See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Cells Mediating Immune Defenses 2 Cytokines 3 Nonspecific Immune Defenses • These defenses recognize some general property marking the invader as foreign and they protect the body as the first line of defense. • The nonspecific defenses include: – Physical barriers – Inflammation – Interferons – Natural killer cells – Complement system 4 Defenses at Body Surfaces • The body’s first lines of defense against microbes are the barriers offered by surfaces exposed to the external environment and their various antimicrobial secretions. • Examples: skin and mucous membranes 5 Inflammation 6 Phagocytosis Fig. 18-2 7 Role of Phagocytosis Fig. 18-3 8 Oponization Fig. 18-4 9 Complement System • The complement system is composed of plasma proteins that lyse foreign cells, especially bacteria. • Approximately 30 proteins participate in the cascades that result in a Membrane Attack Complex (MAC) on the surface of the invading bacteria. • The MAC ruptures the bacterial membrane causing lysis of the bacteria and death of the organism. 10 Functions of Complement Fig. 18-5 11 Interferons Fig. 18-6 12 Specific Immune Defenses: Overview • Lymphocytes recognize specific foreign molecules called antigens. 13 Lymphoid Organs Fig. 18-714 Lymphoid Tissues • Primary Lymphoid organs: – Bone marrow – Thymus • Secondary Lymphoid Organs: – – – – – – Spleen Lymph nodes Tonsils Adenoids Appendix Peyer’s patches 15 Lymphocyte Origins Fig. 18-8 16 Functions of B Cells and T Cells Fig. 18-9 17 Lymphocyte Receptors (Antibodies) Two heavy chains Two light chains Constant region— same within a class of antibodies Variable region— differs for different antigens, gives specificity to antigen-binding site Two antigen-binding sites Fig. 18-10 18 Antibody Function in Humoral Immunity • The antibody functions to bind the specifc antigen. • This leads to inactivation and destruction of the foreign antigen. • There are 5 classes of antibodies: – IgG – IgM – IgE – IgD – IgA 19 Antibody Functions • Neutralization • Agglutination • Opsonization • Complement Activation • Enhanced Natural Killer Cell Activity 20 Major Histocompatibility Complex (MHC) Molecules • There are two classes of MHC molecules: – Class I MHC are expressed on the surface of all nucleated cells. – Class II MHC are expressed on the surface of macrophages, activated B cells, activated T cells, and thymus cells. • T cells have antigen receptors which recognize antigens only when they are associated with MHC molecules. This is part of the antigen presentation mechanisms. 21 MHC is the “Self” Recognition • MHC molecules are unique to each individual person and are also known as HLA (human leukocyte antigen). • These markers are important because they mark cells as “self” or belonging to that organism. • Cells that do not match the MHC are foreign and are responsible for tissue or organ rejection because they stimulate the immune response to foreign tissue. 22 Antigen Presentation to T Cells Fig. 18-11 23 Activation of Helper T Cells Fig. 18-12 24 Cytotoxic T Cells Fig. 18-13 25 NK Cells • NK cells are a class of lymphocytes similar to cytotoxic T cells, whose major targets are virus-infected cells and cancer cells; however, they are not antigen-specific. 26 Development of Immune Tolerance • Immune tolerance develops during fetal and early postnatal life due to clonal deletion or clonal inactivation. • Autoimmune diseases are caused by failure of self-tolerance. 27 Defenses Against Bacteria, Extracellular Viruses, and Toxins Fig. 18-14 28 Enhancement of Phagocytosis by Antibodies Fig. 18-15 29 Activation of Complement Fig. 18-16 30 Defenses Against Virus-Infected Cells and Cancer Cells Fig. 18-18 31 Role of IL-2 and Interferon-gamma Fig. 18-19 32 Memory • Primary immune response: (1st exposure) – Generally takes 10–17 days to occur after exposure – Symptoms of illness occurs during these days – Antigen-selected B and T cells proliferate and differentiate into effector cells • Secondary immune response: (all other exposures) – Takes 2–7 days to occur – Greater response – Occurs due to memory cells 33 Memory Fig. 18-17 34 Systemic Manifestations of Infection Fig. 18-20 35 Factors that Alter the Body’s Resistance to Infection • Factors include nutrition, pre-existing disease, stress, physical exercise, sleep deprivation, and genetic deficiency. 36 Immunity • Active immunity is an immune response to vaccine or pathogen in an individual and gives immunity because of the production of memory cells. • Vaccine is the introduction of a microorganism or its antigens in a form not expected to cause disease, which induces an immune response including production of memory cells 37 Immunity • Passive immunity comes from the administration of synthetically produced antibodies. • This results in no memory cell production, so there is no long-term memory and immunity. • Passive immunity can also come from mother to fetus or baby because antibodies pass in the placenta (IgG) and breast milk (IgA). 38 Harmful Immune Responses • Graft Rejection • Transfusion Reactions • Allergy (Hypersensitivity) • Autoimmune Disease • Excessive Inflammatory Responses 39 Tissue Grafts and Organ Transplantation • HLA molecules (MHC) stimulate rejection by inducing immune response, so there must be as close a match in the MHC between the donor and recipient as possible. • The recipient will have to suppress the immune system pharmacologically to prevent rejection. – Cyclosporin A – FK506 40 Transfusion Reactions • Transfusion reactions are the illness caused when erythrocytes are destroyed during blood transfusion. • It is caused by antibodies rather than cytotoxic T cells. • Erythrocytes do not have MHC proteins, but they do have plasma membrane proteins and carbohydrates that can function as antigens. • The ABO system of carbohydrates is the most important for transfusion reactions. • Another group of erythrocyte membrane antigens of medical importance is the Rh system of proteins. 41 Blood Typing 42 Immediate Hypersensitivity Allergic Response Fig. 18-21a 43 Anaphylactic Shock • Anaphylatic shock is a severe allergic reaction that results from a massive release of histamine from mast cells throughout the body. This causes a massive drop in systemic blood pressure and can cause circulatory collapse. 44 Autoimmune Diseases • The immune system treats a part of itself like an invading pathogen. • Examples: – Insulin-dependent diabetes mellitus (type I) – Lupus – Rheumatoid arthritis – Multiple sclerosis 45 Immunodeficiency Diseases • Immunodeficiency diseases result from weak or under-active immune systems. • Examples: – SCID = severe combined immunodeficiency disease – Hodgkin’s Disease = cancer of lymphatic system – AIDS = affects helper T cells 46 Acquired Immune Deficiency Syndrome (AIDS) • Human immunodeficiency virus (HIV) infects and kills helper T cells resulting in impairment of the immune response to other infectious organisms. 47