Specific Immune system

Cards (12)

  • Cell-mediated immunity:
    • Macrophages engulf and digest pathogens in phagocytosis and process the antigens to form antigen presenting cells (APCs).
    • The receptors on some of the T helper cells fit the antigens. These T helper cells become activated and produce interleukins which stimulate T cells to divide rapidly by mitosis.
    • The cloned T helper cells may; develop into T memory cells, produce interleukins that stimulate phagocytosis, produce interleukins that stimulate B cells to divide or develop into T killer cells and destroy infected cells.
  • Humoral Immunity:
    1. A B cell with the complementary antibody will bind to the pathogen, engulf it and process the antigens to become an APC
    2. Activated T helper cells bind to the B cell APC (clonal selection)
    3. Interleukins produced by the activated T helper cells activate the B cells
    4. The activated B cells divide to give clones of plasma cells and B memory cells (clonal expansion)
  • Humoral Immunity:
    Cloned plasma cells produce antibodies that fit the antigens on the surface of the pathogen, bind to the antigens and disable them or act as opsonins or agglutinins. (primary immune response)Some cloned B cells develop into B memory cells. If the body is infected by the same pathogen again, the B memory cells divide into plasma cell clones. These produce the right antibody and wipe out the pathogen quickly. (secondary immune response)
  • B lymphocytes mature in the bone marrow.
  • T lymphocytes mature in the thymus gland.
  • T helper cells = produce interleukins (a type of cytokine- cell-signalling molecule). These interleukins stimulate the activity of B cells and stimulate the production of other T cells.
  • T killer cells = these destroy the pathogen carrying the antigen. They produce perforin, which kills the pathogen by making holes in the cell membrane so it is freely permeable.
  • T memory cells = live for a long time so if they meet an antigen a second time, they divide rapidly to form a huge number of clones of T killer cells that destroy the pathogen.
  • T regulatory cells = these cells suppress the immune system, acting to control and regulate it. They stop the immune response once a pathogen has been eliminated, and make sure the body recognises self antigens and does not set up an autoimmune response.
  • Plasma cells = produce antibodies to a particular antigen and release them into the circulation.
  • B effector cells = these divide to form the plasma cell clones
  • B memory cells = programmed to remember a specific antigen and enable the body top make a very rapid response when a pathogen carrying that antigen is encountered again.