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Cell mediated and humoral

Cell mediated
1. Process
2. Antigens
  1. Any part of an organism recognised as foreign by the immune system
  2. Proteins that are part of the cell surface membrane
  3. Their presence triggers the production of an antibody as part of the bodys defence system
3. Lymphocytes
  1. The body also has specific responses to react to infection
  2. These are slower at first but can provide long term immunity
  3. Depends on white blood cells called lymphocytes
  4. Two types, each with its own immune response
  5. B cells
    1. Humoral immunity, involving antibodies present in body fluids
    2. Matures in bone marrow
    3. Produces antibodies
    4. Responds to foreign material outside cells
    5. Responnds to bacteria and viruses
  6. T cells
    1. Cell mediated, involving body cells
    2. Matures in thymus gland
    3. Responds to foreign material inside cells
    4. Responds to own cells altered by viruses or cancer and to transplanted tissues
4. How T Cells distinguish
  1. Phagocytes that have engulfed and broken down a pathogen present some of the pathogens antigens on their own surface membrane
  2. Body cells invaded by a virus present some of the viral antigens on their own surface as a sign of distress
  3. Cancer cells present antigens on their own cell surface membrane
  4. These cells are called antigen-presenting cells because they can present antigens of other cells on their own surface
5. Types of T cells
  1. Cytotoxic
    1. Combine with antigens
    2. Release lymphokines
    3. Make holes in membrane
    4. Freely permeable
  2. Helper
    1. Co-operate with B cells in antibody production
    2. Activate macrophages
    3. Promote inflamation
  3. Suppressor
    1. Keep immune system in check
  4. Memory
    1. Remain after pathogen has gone
    2. Produce rapid response to future infection
Humoral
1. Process
2. Types of B cells
  1. Plasma
    1. Sercrete antibodies directly
    2. Only survive a few days
    3. Antibodies destroy the pathogen and any toxins it produces
    4. Primary immune response
  2. Memory
    1. Live often for decades
    2. Don't directly produce antibodies
    3. Circulate in blood and tissue fluid
    4. Divide rapidly and develop into plasma cells
    5. Plasma cells then produce antibodies
    6. Long term immunity
    7. Secondary immune response
      1. More rapid
      2. Greater intensity
3. Antigenic variability
  1. Some pathogens have different strains
  2. Antigens are constantly changing
  3. Subsequent infections likely to be caused by a different variety of pathogen
  4. Antigens will not correspond to antibodies or the memory cells formed during previous infections
  5. No appropriate memory cells, so primary response must be used
4. Humoral
  1. Involves antibodies which are soluable in blood and tissue fluid
  2. When an antigen enters the blood or tissue fluid, there will be one type of B cell that has an antibody whose shape exactly fits the antigen
  3. Antibody attaches to appropriate antigen
  4. B cell divides by mitosis to form a clone, which produce antibodies
  5. Toxins also act as antigens

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Cell mediated and humoral

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	Created by Beth Ritchie over 10 years ago