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Innate vs. Acquired Active vs. Passive Natural vs. Artificial. Types of Immunity. Antigens. Antigens Epitopes Haptens. Antibodies and Cells. B lymphocytes T lymphocytes 4 sub-types Natural Killer cells. Nature of the Immune system. Humoral Immunity Cell-mediated Immunity
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Innate vs. Acquired Active vs. Passive Natural vs. Artificial Types of Immunity
Antigens • Antigens • Epitopes • Haptens
Antibodies and Cells • B lymphocytes • T lymphocytes • 4 sub-types • Natural Killer cells
Nature of the Immune system • Humoral Immunity • Cell-mediated Immunity • Cell lysis, apoptosis • Foreign eukaryotic cells
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
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
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 Nature of the Immune systemClonal stimulation
Heavy/Light Chains Variable/ Constant Regions Antigen Binding Site Disulfide Bridges Antibody Anatomy
Ig G IgA Ig M Ig E (reagin) Ig D Immunoglobulin Classes
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 Immune Memory
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 Antigen Types
Agglutination Reduction of target count Neutralization Viral and bacterial binding sites for host cell attachment are blocked Complement-mediated effects FC fragment (Constant region) activates complement Cytolysis Opsonization Increased inflammation Effects of Ag/Ab Reactions
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 Monoclonal Antibodies
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
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 T Cell Types
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 T Cell Types (cont.)
Mucosal Immune System • Mostly IgA production • 400 square meters (4500 square feet!) • Gut, GUT, Resp. tract
Disorders/Injuries Genetic tendencies Genetic diseases Environment Seasonal Pollution Rediation Lifestyle Diet Exercise Addictions Age Middle life most healthy Factors Modifying the Immune System
Active Ag administration Toxoid or microbial structural molecule Live vaccines provide longer protection Route of administration affects protection level Passive Ab administration Temporary, protection declines Will affect the course of a disease Allergic reactions are commonest drawback Immunization
Future Considerations • Criteria for new vaccines
Bacteria Viruses Fungi Protozoa/Helminths Immunity to Specific Pathogens