Acquired Immunity: Humoral Response Distinction of Humoral versus Cell-Mediated Acquired Immunity Antigens and Antigenic Determinants: Non-self and MHC proteins Cell Types of the Humoral Response and How they Develop B and T cell receptors and immunglobulins (antibodies) Antibody Structure and Classes Activation of B cells and Clonal Selection Immunity and Secondary Response Time Antibody Actions Passive and Active Immunity Monoclonal Antibodies Cell-Mediated Immune System: T cells, Grafting

Body Defenses: Innate and Acquired Defense Systems of the Body  Non-specific defense system (Innate Immune System) Mechanisms protect against a variety of invaders Responds immediately to protect body from foreign materials (Innate immunity)  Specific defense system (Acquired Immune System: Humoral and Cell-Mediated) Specific defense is required for each type of invader Also known generically as just “the immune system”

Nonspecific (Innate) Body Defenses Mechanical, Chemical, and Competitive Barriers Saliva and tears destroy bacteria because they contain lysozyme. Skin produces acidic sebum to limit bacterial growth and sebum fatty acids are fungistatic, urine, blood, saliva Nitric oxide (NO) released by macrophages inhibit ATP production Iron-binding proteins in blood block microbial reproduction

Inflammation Figure 16.9c, d

 Serum proteins activated in a cascade.  Results: Opsonization Chemotaxis Transmembrane channel formation in cells tagged by antibodies (causing cytolysis) Triggers inflammation The Complement System Figure 16.10

Body Defenses: Innate and Acquired Defense Systems of the Body  Non-specific defense system (Innate Immune System) Mechanisms protect against a variety of invaders Responds immediately to protect body from foreign materials (Innate immunity)  Specific defense system (Acquired Immune System: Humoral and Cell-Mediated) Specific defense is required for each type of invader Also known generically as just “the immune system”

Acquired Immune System – Third Line of Defense  Antigen specific – recognizes and acts against particular foreign substances  Systemic – not restricted to the initial infection site  Has memory – recognizes and mounts a stronger attack on previously encountered pathogens The Acquired Immune System is:

Types of Acquired Immunity 1. Humoral Immunity Antibody-mediated immunity in blood and lymph Cells produce chemicals for defense 2. Cellular immunity of the Cell- Mediated Immune System Cell-mediated immunity Cells target virally infected cells

Antigens (Nonself)  Antigen: Any substance capable of exciting the immune system and provoking an immune response  Examples of common antigens Foreign proteins Nucleic acids Large carbohydrates Some lipids Pollen grains Microorganisms  Antigenic determinants: substances (like glycoproteins) on the surface of antigens to which the immune system actually responds Receptor in the immune system that "fits" the antigenic determinant Antigen Antigens

Self-Antigens  Human cells have many surface proteins called major histocompatability complexes (MHC).  All body cells have MHC Class I proteins.  Our immune cells do not attack our own proteins  Our cells in another person’s body can trigger an immune response because they are foreign Restricts donors for transplants

Allergies  Many small molecules (called haptens or incomplete antigens) are not antigenic, but link up with our own proteins  The immune system may recognize and respond to a carrier-hapten combination  This immune response can be harmful rather than protective because it can attack small molecules mounted on our own cells or small molecules normally found in the environment that bind to carriers  allergy or autoimmunity

Humoral (Innate) Immune Response Distinction of Humoral/Innate versus Cell-Mediate Response Antigens and Antigenic Determinants: Non-self and MHC proteins Cell Types of the Humoral Response and How they Develop B and T cell receptors and immunglobulines (antibodies) Antibody Structure and Classes Activation of B cells and Clonal Selection Immunity and Secondary Response Time Antibody Actions Passive and Active Immunity Monoclonal Antibodies

Cells of the Immune System  Lymphocytes Originate from hemocytoblasts in the red bone marrow B lymphocytes become immunocompetent in the bone marrow T lymphocytes become immunocompetent in the thymus  Macrophages (certain mature granulocytes) Arise from monocytes Become widely distributed in lymphoid organs

Development of Lymphocytes T cell maturation and "education"

B Cell Receptors, T Cell Receptors, and Immunoglobulins B cell Secreted (Exported) Immunoglobulin or Antibody (Same V and C Regions as in B cell receptors) Variable (binding) regions Receptors on T Cells Constant regions Receptors on B cells T cell

Humoral (Innate) Immune Response Distinction of Humoral/Innate versus Cell-Mediate Response Antigens and Antigenic Determinants: Non-self and MHC proteins Cell Types of the Humoral Response and How they Develop B and T cell receptors and immunglobulines (antibodies) Antibody Structure and Classes Activation of B cells and Clonal Selection Immunity and Secondary Response Time Antibody Actions Passive and Active Immunity Monoclonal Antibodies

Immunoglobulins and Receptors Bind To Antigens Agglutination of antigens

Different Classes of Antibodies

Humoral (Innate) Immune Response Distinction of Humoral/Innate versus Cell-Mediate Response Antigens and Antigenic Determinants: Non-self and MHC proteins Cell Types of the Humoral Response and How they Develop B and T cell receptors and immunglobulines (antibodies) Antibody Structure and Classes Activation of B cells and Clonal Selection Immunity and Secondary Response Time Antibody Actions Passive and Active Immunity Monoclonal Antibodies

B Cell Activation and Clonal Selection Humoral immunity movie

Secondary Response (Immunity) Figure 12.13

Results of Antibody Binding to Antigen Agglutination (coralling of the invader) Precipitation (removal of soluble antigens from blood and lymph) Neutralization (blocking antigen's activity and binding) Opsonization (faciliating macrophage phagocytosis) Tagging, complement fixation, and transmembrane channel formation (lysis of pathogen) Agglutination Precipitation (soluble antigens) Transmembrane channel formation and lysis Antibody Function movie

Humoral (Innate) Immune Response Distinction of Humoral/Innate versus Cell-Mediate Response Antigens and Antigenic Determinants: Non-self and MHC proteins Cell Types of the Humoral Response and How they Develop B and T cell receptors and immunglobulines (antibodies) Antibody Structure and Classes Activation of B cells and Clonal Selection Immunity and Secondary Response Time Antibody Actions Passive and Active Immunity Monoclonal Antibodies

Active vs Passive Immunity  Active Immunity Your B cells encounter antigens and produce antibodies Active immunity can be naturally or artificially acquired (e.g via vaccination)  Passive Immunity Antibodies are obtained from someone else oConferred naturally from a mother to her fetus oConferred artificially from immune serum or gamma globulin Immunological memory does not occur Protection provided by “borrowed antibodies”

Monoclonal Antibodies  Antibodies prepared for clinical testing or diagnostic services  Produced from descendents of a single cell line  Examples of uses for monoclonal antibodies Diagnosis of pregnancy Treatment after exposure to hepatitis and rabies HIV/AIDS detection in ELISA Assays

Humoral (Innate) Immune Response Distinction of Humoral/Innate versus Cell-Mediate Response Antigens and Antigenic Determinants: Non-self and MHC proteins Cell Types of the Humoral Response and How they Develop B and T cell receptors and immunglobulines (antibodies) Antibody Structure and Classes Activation of B cells and Clonal Selection Immunity and Secondary Response Time Antibody Actions Passive and Active Immunity Monoclonal Antibodies

Cell Mediated Immune Response  Players in the Cell Mediated Response  Activation of Cytotoxic T and B cells via T H cells  Other T cells and their function  Tissue grafting

Cellular (Cell-Mediated) Immune Response 1. Antigens must be presented by macrophages to an immunocompetent T cell (antigen presentation) 2. T cells must recognize non-self antigen and self MHC proteins (double recognition) 3. After antigen binding, clones form as with B cells, but different classes of cells are produced

Activation of T and B Cells Through T H cells MHC "self" identifying protein

Types of T Cells  Cytotoxic T (T c ) cells Specialize in killing infected cells Insert a toxic chemical (perforin)  Helper T (T H ) cells Recruit other cells to fight the invaders Interact directly with B cells  Suppressor T cells Release chemicals to suppress the activity of T and B cells Stop the immune response to prevent uncontrolled activity  A few members of each clone are memory cells Helper t cells animation Cytotoxic t cells animation

Summary of B Cell Activation  B cells can be activated directly by antigen or from a TH cell activated by an antigen-presenting macrophage

Summary of the Immune Response

Organ Transplants and Rejection  Major types of grafts Autografts – tissue transplanted from one site to another on the same person Hey buddy, my patch of skin is damaged! Can I have your autograft? Isografts – tissue grafts from an identical person (identical twin) Allografts – tissue taken from an unrelated person (sometimes successful) Xenografts – tissue taken from a different animal species (rarely successful)