BIOL 320 1st EditionLecture 12Outline of Last Lecture I. Specific Lymphoid TissuesII. Lymphatic PathologyIII. Developmental Aspects of Lymphatic SystemI. Immune Systema. Functionsb. Innate Defensesi. Surface Barriersii. Internal Defensesc. Adaptive DefensesOutline of Current Lecture II. Internal Defensesa. Tissue Injury  Healingb. Phagocytic MobilizationIII. Adaptive Defensesa. Antigensb. Cells of Adaptive Immune Systemc. Humoral Immune Responsed. Cell Mediated Immune Responsee. Homeostatic ImbalanceCurrent LectureInnate Defenses:- Internal Defenseso Tissue Injury  Healingo Phagocytic Mobilization- 1) Leukocytosis: neutrophils enter blood from bone marrow- 2) Margination: neutrophils cling to capillary wall- 3) Diapedesis: neutrophils flatten and squeeze out of capillaries- 4) Chemotaxis: neutrophils follow chemical trailo Inflammatory chemical diffusing from the inflamed site act as chemotactic agentso Antimicrobial Protein- Interferons: help neighboring cells resist attack…medical use (Hepatitis C and Herpes virus)- Complement: amplifies inflammatory response- Fever: induced by pyrogins…pyrogins act on hypothalamus to raise temperature…sequester iron and zinc in liver and spleen (starve microbes) and allow unfavorable temperature for microbes- Steps for Interferon Response:o 1) Virus enters cello 2) Interferon genes switch ono 3) Cell produces interferon moleculeso 4) Interferon binding stimulates cell to turn on genes for antiviral proteinso 5) Antiviral proteins block viral productionAdaptive Defenses- Key Features:o 1) SPECIFICo 2) SYSTEMICo 3) MEMORY- Divisions:o 1) HUMORALo 2) CELLULAR- Functions:o 1) Immobilize, neutralize/destroyo 2) Amplify inflammatory responseo 3) Activates complement- "Self": cells cover selves with major histocompatibility complex (MHC) = glycoprotein (self-antigen = unique to individual)…MHC I on all body cells…MCH II only on certain tissue cells- Antigens:o Antigens: can mobilize adapt. Defense & provoke immune responseo Complete Antigens: Immunogenicity (stimulate lymphocyte proliferate lymphocytes) Reactivity (can react with lymphocytes & antibodies)o Haptens: small molecules (only immunogenic when attached to body proteins)o Antigenic Determinants: where antibodies & lymphocyte receptors bind Ex: Knee replacements: metals and plastics are large simple molecules that aren't immunogenic and don't have binding sites (antigenic determinants)- Cells of Adaptive Immune Systemo *Requires activation to interpret antigens (in lymphoid tissues)*o CELLS: B Lymphocytes: recognize & bind to foreign antigens in fluids- Produced and mature in: bone marrow- Oversee: humoral immune response (in response to bloodstream) T Lymphocytes: recognize fragments of foreign antigens [on APCs (antigen preventing cells)]- Produced in: bone marrow- Mature in: thymus- Oversee: cell-mediated immune response- Selection process: eliminate cells that attack self…want a population that recognize foreign antigens well and not as picky with self cells- Antigen Presenting Cells- Functions:o Engulf foreign cellso Present foreign antigen on own plasma membrane to be recognized by T cells- Major APCs:o Dendritic cells (DC)o Macrophageso Activated B cells- Major initiators of adaptive immunity: DCs (& macrophages) secrete particles that activate T cells- Activated T cell response:o 1) Speed DC maturationo 2) Stimulate macrophage activationo Immunocompetence: have the ability to carry out immune response when properly stimulated 1) Lymphocytes destined to become T cells migrate (in blood) to the thymus and develop immunocompetence there. B cells develop immunocompetence in red bone marrow. 2) Immunocompetent but still naïve lymphocytes leave the thymus and bone marrow. They “seed” the lymph nodes, spleen, and other lymphoid tissue where they encounter their antigen. 3) Antigen-activated immunocompetent lymphocytes (effector cells and memory cells) circulate continuously in the bloodstream and lymph and throughout the lymphoid organs of the body.- Humoral Immune Response- Cell Mediated Immune Response- Homeostatic