Enhancing immunity

• What is an antigen?

  Cell-surface molecule stimulating immune response
• What types of molecules can be antigens?

  (Glyco)proteins, (glyco)lipids, or polysaccharides
• How does the immune system recognize antigens?

  As “self” or “non-self” entities
• What does the recognition of antigens enable?

  Identification of cells from other organisms
• What is the first step in phagocytosis?

  Phagocyte moves towards pathogen via chemotaxis
• What happens after a phagocyte engulfs a pathogen?

  It forms a phagosome
• What occurs when a phagosome fuses with a lysosome?

  It forms a phagolysosome
• What is the role of lysozymes in phagocytosis?

  They digest the pathogen
• What does a phagocyte do after digesting a pathogen?

  Absorbs the products from pathogen hydrolysis
• What is the role of antigen-presenting cells (APCs)?

  Display antigens from pathogens on their surface
• How do APCs enhance recognition by TH cells?

  By displaying antigens after hydrolysis
• What are two differences between specific and nonspecific immune responses?

  Nonspecific is immediate; specific has a time lag
• What are the two types of specific immune response?

  Cell-mediated and humoral
• What is the first step in the cell-mediated response?

  TH lymphocytes bind to foreign antigen on APC
• What do TH lymphocytes release to stimulate clonal expansion?

  Cytokines
• What happens during clonal expansion of TH cells?

  They undergo rapid mitosis to become memory cells
• What do cytotoxic T cells secrete to destroy infected cells?

  Enzyme perforin
• What is the first step in the humoral response?

  TH lymphocytes bind to foreign antigen on T cells
• What do B cells differentiate into during the humoral response?

  Plasma cells
• What do plasma cells secrete?

  Antibodies with complementary variable region
• What are antibodies?

  Proteins secreted by plasma cells
• What is the structure of an antibody?

  Two light chains and two heavy chains
• What is the role of the variable region of antibodies?

  Binding sites complementary to an antigen
• How do antibodies lead to pathogen destruction?

  Formation of antigen-antibody complex results in agglutination
• What are monoclonal antibodies?

  Antibodies produced from a single clone of B cells
• What are memory cells?

  Specialized TH/B cells from primary immune response
• What do memory cells do upon re-encountering a pathogen?

  Divide rapidly by mitosis
• What are the characteristics of the secondary immune response?

  Faster rate, shorter time lag, higher antibody concentration
• What causes antigen variability?

  Random genetic mutation changes DNA base sequence
• How does antigen variability affect immunity?

  Memory cells may not recognize new antigens
• What are the implications of antigen variability for vaccines?

  Difficult to develop vaccines for all antigen types
• What is passive immunity?

  Involves antibodies from an external source
• What is active immunity?

  Involves lymphocytes producing antibodies
• What is an example of passive natural immunity?

  Antibodies in breast milk
• What is an example of active artificial immunity?

  Vaccination
• What is the difference in memory cell production between passive and active immunity?

  Active produces memory cells; passive does not
• What is the principle of vaccination?

  Triggers primary immune response with a vaccine
• What is herd immunity?

  Vaccinating large population reduces pathogen carriers
• What are some ethical issues surrounding vaccines?

  Use of animals and potential side effects
• What is the structure of HIV?

  Genetic material and viral enzymes in a capsid