New Page 1 IMMUNITY Susceptibility: Lack of resistance to a disease. Effected by: General health Nutrition Age Stress Resistance: Ability to ward off disease. ________________________________________resistance : Generally present Defenses against any pathogen (not directed toward any particular pathogen) Specific resistance: Immunity, resistance to a specific pathogen INNATE RESISTANCE/IMMUNITY Species: Pathogens may only infect a limited range of species. e.g. Mumps: Infects humans not dogs or cats. Anthrax: Cattle and humans but not birds. Reasons for species resistance (Many unknown) Physiology: e.g. Anthrax: _________________________________________ is the key! Humans: 37oC Birds: 41-45oC Pasteur exposed chickens to anthrax and then lowered their body temperature. The chickens died of anthrax. b. Anatomy: e.g. Plant diseases (Certain chemical receptors plant pathogens require do not exist in/on the human body.) c. Behavior/Diet: e.g. Fish tapeworm Diphyllobotrium latum. Ingested in raw fish. Any species that doesn’t eat fish is unlikely to get this disease. 2) Race or Strain e.g. Caucasians are more susceptible to diphtheria, influenza, and gonorrhea. Blacks and American Indians are more susceptible to TB. 3) ___________________________________________: Hormone levels affect the immune system. Mechanical/Physical Barriers Intact skin: Epidermis consists of tightly packed cells with Keratin, a protective protein. Acts as a barrier to most microbes. 2) Mucous membranes: Line body cavities that open to the exterior. e.g. Digestive, respiratory, urinary, and reproductive tracts. The epithelial layer of mucus membranes secretes mucus which acts as a trap and physical barrier. Much less protective than skin. 3) Hairs of the Ears and Nose: Filter and trap microbes. 4) Ciliary/Mucociliary escalator: Microbes trapped in mucus are transported away from the lungs. 5) __________________________________________apparatus: Manufactures and drains away tears. Continual washing of the eyes. 6) Salivary glands: Wash microbes from teeth and mucus membranes of the mouth. 7) Urine: Flow of urine moves microorganism out of the urinary tract. 8) Vaginal secretions: Help remove microorganism from of the vagina. 9) Reflexes: Coughing Sneezing Vomiting Diarrhea (2 CHEMICAL DEFENSES Sebaceous Glands: Secrete sebum: contains fatty acids: gives the skin a low pH (3-5) Sweat Glands: Produce perspiration contains: NaCl and lysozyme Gastric Juice: Contains HCl low pH (1.2-3.0) Transferrins: Iron-binding proteins in the blood. Limits available iron needed for microbial growth. Blood: The Fluid Portion Plasma and Serum Formed Elements Erythrocytes (RBCs) Leukocytes (WBCs) Thrombocytes/Platelets Leukocytes (WBCs) Granulocytes: Have granules in the cytoplasm and a lobed nucleus. 1) Neutrophiles (PMNs) 2) Basophils 3) Eosinophiles __________________________________________ 2 Types 1) Monocytes/Macrophages 2) Lymphocytes Differential Blood Count Determines the relative percent of each WBC type. Many infections cause an increase or decrease in WBC numbers. Leukocytosis: Increase in total WBC count. _____________________________________________: Decrease in WBC count. Neutrophilia: Increase Neutrophile count. >10% Bands = Infection or inflammation. Neutropenia: Decrease in Neutrophil count. Eosinophilia: Increased Eosinophil count. e.g. Allergies and Parasitic infections Lymphocytosis: Increased Lymphocyte count. Functions of WBCs Neutrophils: __________________________________________ Basophils/Mast Cells: Produce histamine Eosinophils: Toxic to parasites, some phagocytosis Monocytes: Phagocytic as mature macrophages Lymphocytes: Involved in specific immunity Mononuclear Phagocytic/ Reticuloendothelial System (RES) Consists of phagocytes which enter certain tissues and remain there: Fixed Macrophages/Histocytes: Ingest bacteria and debris as they flow past. Found in the Liver: Kupffer cells Lungs: _________________________________________________ Macrophages Nervous system: Microglial cells Skin: Langerhan’s cells Also located in Spleen, Lymph nodes, bone marrow and peritoneal cavity. Other macrophages are called wandering macrophages. PHAGOCYTOSIS INFLAMMATORY RESPONSE Response to tissue damage by a combination of nonspecific defenses. Characterized by: Redness (Rubor), Pain(Dolor), Heat (Calor), Swelling (Tumor/Edema) (3 Functions of Inflammation Destroy the injurious agent, and remove it. 2) Confining or walling off the injurious agent and it’s by products. 3) To repair or replace damaged tissues. In response to injury _____________________________________proteins (complement, cytokine, fibrinogen and kinins) are activated and their concentration increases. _____________________________________________ Injured tissues release: Histamine, Kinins, Prostaglandins, Leukotrienes These substances dilate (increase the diameter) of blood vessels Redness and Heat Increased permeability: Margination and emigration/diapedesis of WBCs Increased WBCs at site of injury PMNs reach site first (Short lived) Monocytes reach site within 24hr. (Longer lived) _______________________________________________: Increased flow of fluids from blood to tissue spaces. Tissue Repair: The final stage of inflammation. Begins during the active phase of inflammation. Fever (Systemic increase in body temperature) Endogenous Pyrogens (Interlukin 1) IL-1 and alpha tumor necrosis factor. Secreted by WBCs (Monocytes & Macrophages) Act on the hypothalamus (Body's thermostat) Hypothalamus releases prostaglandins. Increase in body temperature. Inhibits the growth of some organisms. Speeds up body's chemical reactions. Decreases available iron. When IL-1 is eliminated, body temperature falls. (Crisis) ________________________________________________________System A group of over 30 proteins found in the blood. Complements antigen antibody reactions. Binds to immune complexes. Several functions: Cell lysis: Membrane attack complex WBC chemotaxis: Attracts phagocytes Opsonization or immune adherence: enhanced phagocytosis Inflammation. Interferons (IFNs) Alpha IFN & Beta IFN: Cause cells to produce antiviral proteins that inhibit viral replication Gamma IFN: Increases the activity of neutrophils and macrophages in phagocytizing bacteria. (4 SPECIFIC HOST DEFENSES Immune System: 2 Parts 1) Humoral Immune System: Involves specific antibodies in the blood and lymph. (The body's humors) Produced by B cells. 2) Cellular Immune System: Involves T cells. That do not produce antibodies but secrete cytokines. Specialized lymphocytes respond to intracellular Ags T cells mature in the _________________________________________. After maturation they migrate to lymphoid tissue. Kinds of Immunity Innate Immunity and Acquired Immunity Acquired Immunity : Resistance to infection due to activity of ___________________________________ a) Active Immunity b) Passive Immunity Naturally Acquired _________________________________________Immunity 1) Stimulus : Contact with a live microbe by natural processes. e.g. Infection; illness 2) Response : Symptoms of disease or subclinical RXN Active production of specific antibodies to the pathogen. 3) Duration : Long term (months - years), sometimes life long. Lots of exceptions: e.g. Influenza ___________________________________________ Acquired Active Immunity Antigen is intentionally introduced into the body. 1) Stimulus : Vaccines/Immunization: a) Killed pathogens (or their proteins alone) b) Attenuated/weakened live pathogens c) Inactivated toxins (toxoids) 2) Response : Production of specific antibodies without developing symptoms of disease (or prodromal symptoms only) 3) Duration : Variable (Months-years-life time) ____________________________________Immunity : Immunity acquired through transfer of antibodies. Naturally Acquired Passive Immunity 1) Mother to fetus through the placenta (placental transfer) or in colostrum/milk during nursing. 2) Response : No immune response. Acquisition of antibody only. 3) Duration : Short term (a few weeks -months) Artificially Acquired Passive Immunity 1) Antibodies formed in one individual transferred/injected into another individual. Immune serum/gamma globulin 2) Response : No immune response, acquisition of antibody only. 3) Duration : Very short (2-3 weeks) e.g. Venomous snake bites, Tetanus, Hep. A, Diphtheria, Botulism. ANTIGENS AND ANTIBODIES Specific immune response involves production of ___________________________________ antibodies (Ab) against specific antigens (Ag). (5 The nature of antigens/Immunogens 1) Definition: An ___________________________________________is any substance that when introduced into the body stimulates the production of specific antibodies. An antigen is any substance that combines with those specific antibodies. The term antigen is often used to mean both an antigen and an immunogen. 2) Characteristics : Foreign/Non-self matter e.g. Microorganisms, toxins, foreign tissues. Chemically : Complex molecules: e.g. Protein or polysaccharide ____________________________________________________antigen: Has reactivity (combines with specific antibodies) without immunogenicity (stimulating production of specific antibodies) unless bound to a carrier. Antigenic ________________________________________________ Antibodies are not formed against a whole organism but specific regions or chemical groups. Nature of Antibodies/Immunoglobulins Definition: A protein produced by B lymphocytes in response to an immunogen/antigen and is capable of combing with that antigen. Gamma Globulins: From separation of blood proteins by electophoresis. Antibody structure: Two _______________________________________chains and two light chains. Heavy and light chains both have a “C” or constant portion and a “V” or variable portion. ____________Portion: is different for each kind of Ab and gives the Ab its specificity. Ag binding occurs at the V portion. C Portion: Constant for each class of Ab. ______________________: (Antigen binding fragment) the two “arms” Fc: (Crystallizable fragment) The “trunk” of the antibody. Contains the complement binding site. Classes of Antibody IgG: Monomer 80% of serum antibodies (Most abundant Ab in serum) Can cross the placenta: protects fetus & newborn. Fixes complement. Enhance phagocytosis; neutralize toxins & viruses. Half-life = 23 days _______________ Pentamer 5-10% of serum antibodies Fixes complement In blood, lymph, on B cells. Agglutinates microbes; first Ab produced in response to infection Half-life = 5 days IgA: Dimer: 10-15% of serum antibodies Main Ab in mucus secretions, and breast milk. Mucosal protection.nHalf-life = 6 days IgD: Monomer 0.2% of serum antibodies In blood and lymph.Receptor on B cells.Half-life = 3 days ______________: Monomer 0.002% of serum antibodies On mast cells and basophils, in blood. Allergic reactions; lysis of parasitic worms. Half-life = 2 days Antibody Response (B Cells) 1o Response: Contact with the Ag for the first time. 1) Plasma cells ---> Antibodies 2) Memory cells are formed 2o Response/ Anamnestic Response Memory cells activated ---> Plasma cells ---> Abs formed quickly and in large numbers. (6 SPECIFIC HOST DEFENSES ___________________________________________Immunity Involves interaction of macrophages and specific T lymphocytes (T-Cells) Pathogens entering the gastrointestinal or respiratory tracts pass through: Peyer's patches which contain Dendritic cells: act as antigen-presenting cells. T cells differentiate into _____________________________________ T cells when stimulated by an Ag. Some effector T cells become memory cells. T Cell Types Helper T Cells (CD4, TH) TH1: Activate cells related to cell-mediated immunity TH2: Activate B cells to produce IgM, and IgE ____________________________________________T Cells (CD8, TC) Destroy target cells with perforin. Delayed Hypersensitivity T Cells (TD) Associated with allergic reaction, transplant rejection, and tuberculin skin test. ____________________________________________ T cells (TS) Turns off immune response when Ag is no longer present. Nonspecific Cells Activated macrophages: Macrophages stimulated by ingesting Ag or by cytokines. Natural killer cells: Lymphocytes that destroy virus-infected cells, and tumors. T-dependent Antigens T-independent Antigens Antibody-Dependent Cell-Mediated Cytotoxicity ______________________________________________________ The immune system does not normally attack self tissues or compounds. Clonal deletion: During embryonic development lymphocytes with antigen receptors for molecules present in the body are destroyed. __________________________________________________________(MHC) Human Leukocyte Antigen Complex (HLA) Glycoproteins in plasma membrane that enable the immune system to distinguish self from nonself. Class I MHC: On all nucleated cells. Class II MHC: On macrophages and B cells.
|