Transcript Chapter 17
Types of Immunity Innate vs. Acquired Active vs. Passive Natural vs. Artificial 1 Antigens Antigens Epitopes Haptens 2 Antibodies and Cells B lymphocytes T lymphocytes – 4 sub-types Natural Killer cells 3 Nature of the Immune system Humoral Immunity Cell-mediated Immunity – Cell lysis, apoptosis – Foreign eukaryotic cells 4 General Immune System Properties Self versus Non-self Recognition – Maturation leads to ________________ – Defects = _______________________ Specificity – Random gene rearrangements create potential binding sites for antigens – Some cross-reactivity 5 General Immune System Properties Diversity – Over 1 billion antigen binding sites are possible Memory – Sub-populations of stimulated lymphocytes remain in lymph nodes to provide a faster, larger response on second antigen encounter – Basis of “Immunity” or the anamnestic (secondary) response 6 Nature of the Immune system Clonal stimulation B lymphocyte binds ________ Bound Ag is engulfed and fragmented within the B cell Ag fragments + ____________________________ (MHC II) proteins together = presented or “processed” antigen Triggers __________________ (IL-2) production from T cells This stimulates B cells further and creates memory cells Known as _______________________, usually proteins 7 Antibody Anatomy Heavy/Light Chains Variable/ Constant Regions Antigen Binding Site Disulfide Bridges 8 Immunoglobulin Classes Ig G IgA Ig M Ig E (reagin) Ig D 9 Immune Memory Primary Response – – – – IgM initially IgG detectible in 2-3 weeks Levels may drop after initial exposure Memory cells persist Secondary Response – Much larger response of IgG – Protection against invading microbes and toxins 10 Antigen Types T-independent – No helper T cells – No memory cells are created – Only IgM – Carbohydrate Ag, often capsular on bacteria T-dependent – – – – Needs helper T cells Creates memory B cells IgM and IgG Protein Ag 11 Effects of Ag/Ab Reactions Agglutination – Reduction of target count Neutralization – Viral and bacterial binding sites for host cell attachment are blocked Complementmediated effects – FC fragment (Constant region) activates complement • Cytolysis • Opsonization • Increased inflammation 12 Monoclonal Antibodies MAbs – Multiple myeloma cells + normal lymphocytes – Hybrid cells are • Immortal in large-scale cell culture • Specific Ab producers – Uses • Diagnostic – Pregnancy – Strep. Throat – Chlamydia STD • Anticancer – Chemo agents may be attached • Anti-tissue rejection – Allergies to mouse proteins are a challenge • Humanized Mabs 13 Cell Mediated Immunity Activation – Processed antigens presented alongside MHC proteins • TH cells are activated by Ag + MHC II, antigen presenting dendritic cells, B cells or macrophages • TC cells are activated by Ag + MHC I , usually infected cells with intracellular virus or bacteria, transformed cells or transplant cells Memory T cells can form 14 T Cell Types Helper T cells (TH) release lymphokines – IL-2 • stimulates Ab production • Activates TC cells – Gamma IFN • Co-ordinates inflammatory response • Antiviral and anti-tumor Delayed Hypersensitivity T cell (TD) – TD cells release lymphokines that control macrophage movement/inflammation 15 T Cell Types (cont.) Cytotoxic T cells (TC) – Produce Perforin proteins – Lyse virally infected cells Natural Killer cells – Produce Perforin proteins – Lyse tumor and bacterially infected cells – Activated by lack of MHC proteins on cell membranes, no clonal stimulation 16 Mucosal Immune System Mostly IgA production 400 square meters (4500 square feet!) Gut, GUT, Resp. tract 17 Factors Modifying the Immune System Disorders/Injuries – Genetic tendencies – Genetic diseases Environment – Seasonal – Pollution – Rediation Lifestyle – Diet – Exercise – Addictions Age – Middle life most healthy 18 Immunization Active Passive – Ag administration – Ab administration – Toxoid or microbial structural molecule – Temporary, protection declines – Live vaccines provide longer protection – Will affect the course of a disease – Route of administration affects protection level – Allergic reactions are commonest drawback 19 Future Considerations Criteria for new vaccines 20 Immunity to Specific Pathogens Bacteria Viruses Fungi Protozoa/Helminths 21