B cells & T cells

• structure of antibody

  A = antigen-binding site

  B = disulfide bridge

  C = heavy chain

  D = constant region

  
• what makes up the humoral response

  • primary immune response
  • secondary immune response
• what is meant by the cell mediated response

  immune response involving T cells
• advantage of antibodies having 2 antigen binding sites

  • When mAbs encounter a group of pathogens, each antibody can bind to antigens on 2 different pathogens
  • causing the pathogens to clump together, agglutination
  • This makes it harder for pathogens to spread throughout the body and makes it easier for phagocytes to locate them
• antigen variability

  Mutation on a pathogen means antigens are no longer complementary to receptors on memory b cells or any monoclonal antibodies produced by plasma cells
• Define antibody

  A protein secreted by plasma cells in response to the presence of a specific antigen
• process of primary immune response

  • naive B cell's receptors bind to an antigen on the pathogen
  • B cell internalises the pathogen and breaks it down
  • B cell processes its antigens and presents them on its surface
  • processed antigen binds to complementary receptors on helper T cell
  • T cell releases chemicals which stimulate B cell to clone itself
  • Each clone differentiates into either a plasma cell or memory B cell
• secondary immune response

  involves memory B cells and forms new plasma cells and more memory B cells
• process of cell mediated response

  • helper T cells's bind to the processed antigen on the antigen-presenting phagocyte via complementary receptors
  • This stimulates the T cell to form clones
• things cloned helper T cells stimulate

  • B cells to clone
  • Phagocytosis
  • cytotoxic T cells
• types of T cells

  • Helper T cells
  • Cytotoxic T cells
• How cloned helper T cells stimulate cytotoxic T cells

  • Helper T cell helps T cells to target own infected body cells
  • Cytotoxic T cells have receptors complementary to the antigens present on body cell's surface
  • cytotoxic T cell releases a protein called perforin
  • Perforin causes holes to from in cell membrane
  • This makes it easy for substances to flow in and out of the cell in an uncontrolled way which disruptes the balance in the cell, leading to the infected cell's death