Immunity: Innate and Acquired Immune Systems PDF

 Survival Animals have developed naturally occurring nonspecific defense mechanisms against pathogens as well as complex interactions among different types of immune cells and cellular secretions that target specific pathogens. Two Main...

 Survival Animals have developed naturally occurring nonspecific defense mechanisms against pathogens as well as complex interactions among different types of immune cells and cellular secretions that target specific pathogens. Two Main 1. INNATE IMMUNITY 2. ACQUIRED IMMUNITY Mechanisms Non-specific Acquired immunity is a immunity that specific immunity that consists of a set of displays a high degree of disease-resistance specificity as well as the mechanisms that are property of memory. not specific for a particular antigen. Gettyimages Conceptualization of a lymphoid progenitor cell It is the first line of defense and acquired / adaptive immunity backs it up. Overview of the Immune System (Figure 22.2)  More specifically this is what we want to happen Quick Comparison  INNATE IMMUNITY Rapid EXTERNAL Nonspecific (or generic) and Present at birth INTERNAL Innate Immunity Critical to the defenses – but cannot guarantee protection Lacks flexibility to respond to diverse set of microorganisms and may cause significant tissue damage Activates within hours of the appearance of the antigen  INNATE IMMUNITY Has the following components: Does not require prior exposure to an infectious 1. ANATOMIC agent to be 2. PHYSIOLOGIC effective. 3. CELLULAR 4. CHEMICAL INNATE IMMUNITY IS DIFFERENT FOR EACH SPECIES  Innate Immunity Mechanisms - ANATOMIC a. Unbroken Skin b. Mucous membranes c. Hairs d. Cilia  Innate Mechanisms - PHYSIOLOGIC a. Temperature of skin b. pH (stomach acid) c. Oils (sebum) d. Mucus e. Normal flora f. Sweat i. Lysozyme ii. salts iii. urea iv. lactic acid  Innate Mechanisms - CHEMICAL a. Fever a. Inhibits replication of microbes b. Stimulates wbc to destroy microbes b. Complement a. 30 different proteins in blood plasma (inactive) b. fights bacteria & some fungi in blood c. Interferons a. Group of gylcoproteins released by a variety of cells b. Virus infected cells that produce interferon will die c. But the interferon produced by the infected cell attaches to the membranes of surrounding cells and prevents them being infected.  Innate Immunity: Major Cellular Components Erythrocyte Platelets Neutrophil Eosinophil Basophil WBCs Monocyte Macrophage B-lymphocyte T-lymphocyte  Innate Mechanisms - CELLULAR a. Inflammation b. Phagocytosis 1. local injury/trauma causes a call for beneficial cells+fluids to the site 2. cytokines released by blood + tissue due to swelling etc. 3. neutrophils arrive first then later monocytes and macrophages arrive 4. phagocytic cells must be able to recognize nonself so that only invading particles and abnormal cells (dead) are acted upon.  INNATE IMMUNITY IT IS NOT LONG LASTING DOES NOT INDUCE IMMUNOLOGICAL MEMORY  ACQUIRED IMMUNITY 1. Antibody Specificity 2. Diversity Carefully regulated. 3. Memory Sequential 4. Self-nonself steps.  ACQUIRED IMMUNITY: COMPONENTS 1. Nonself recognition involves proteins imbedded in the cell surface a. Class I on surface of almost all cells b. Class II on certain cells that have a role in the immune system 2. MHC proteins recognized by two basic types of molecules a. Antibodies b. T-cell receptors  ACQUIRED IMMUNITY: COMPONENTS 1. Nonself recognition involves proteins imbedded in the cell surface a. Class I on surface of almost all These proteins are called cells MHC = Major Histocompatibility Complexes b. Class II on certain cells that have These proteins are called a role in the immune system APC’s = Antigen Presenting Cells 2. MHC proteins recognized by two Examples: macrophages, dendritic cells, B cells basic types of molecules *technically APC’s part of Innate system a. Antibodies b. T-cell receptors  ACQUIRED IMMUNITY: CELLS Lymphocytes i. B lymphocytes ii. T lymphocytes Both originate in bone marrow but develop into two distinct types T LYMPHOCYTE – act via activation mechanism to get killer cells B LYMPHOCYTE- act directly on cells to destroy foreign cells Humoral Cell Mediated  CELLS - LYMPHOCYTES B LYMPHOCYTES T LYMPHOCYTES Mature in the bone marrow or +/- Mature in thymus gland lymphoid tissue of gut After maturation each cell type migrates to precise areas in lymphoid tissue until they are needed. B-lymphocytes have antibody T-lymphocytes have surface receptors molecules in their surface and give rise that bind antigens to plasma cells Plasma cells actively secrete antibodies into blood T – cells in action Virus Virus B – cells in action Virus Virus Virus Virus ACQUIRED IMMUNITY: B cells & ANTIBODIES 1. Antibodies – proteins called immunoglobulins 1. They are produced when the B lymphocyte becomes sensitized to a specific antigen 1. The B lymphocyte will rapidly divide and produce A. Plasma cells (aka effector B cells) 1. Live only a few days 2. 2000 antibody molecules per second B. Memory cells 1. Have a longer life span than a naïve B lymphocyte Major Immunoglobulin Classes in Domestic Mammals ACQUIRED IMMUNITY: ANTIBODIES TYPE FUNCTION Immunoglobulin M IgM M is for macro –it’s huge, great capacity to bind to the antigen. 1st antibody produced in response to an Ag, circulates in blood but too large to cross placenta Immunoglobulin G IgG Produced by memory cells responding for the 2nd time to an Ag. Most prevalent. Circulates in blood and is only immunoglobulin to cross the placenta. Immunoglobulin A IgA Secretory immunoglobulin found in mucous and serous secretions, provides local immunity, and is passed to young when nursing. Immunoglobulin D IgD Immunoglobulin found in small amounts in plasma and thought to play a role in immune suppression. Immunoglobulin E IgE Stimulates an inflammatory response and is involved in allergic and parasitic conditions.  ACQUIRED IMMUNITY: T cells T Lymphocyte Function Helper, TH ,or CD4 Assist in immune response and secrete substances that stimulate B lymphocytes. Cytotoxic T cell (killer) Binds tightly to target cell and secretes a protein that causes pores to form in the foreign cell membrane. Short lived. Suppressor T cell, or Inhibits B lymphocytes and the immune response. CD8 Memory T cell Remembers the specific antigen and stimulates a faster and more intense response if the same antigen is presented Maturation of T lymphocytes is very rigid, the cell must be able to: a. Positive selection – respond only to foreign antigens b. Negative selection –will not respond to self antigens A T cell which does not learn this lesson will be terminated by a process called APOPTOSIS. 90% of developing T cells die within the thymus. T – CELL RESPONSE IS VERY RAPID AND VERY DEADLY Tolerance Tolerance Is the name given to the situation where the immune system will not respond to a specific antigen It is primarily directed against self-antigens from normal tissues