Cell recognition and immunity- content

• Self Cells


  The body's own cells and molecules
• Non-Self Cells


  Foreign cells and molecules invading someone
• Non Specific Defense


  A bodily response that is immediate and applies to all pathogens entering the body
• Specific Defense


  A slower bodily response that is specific based on each pathogen entering the body
• Cellular Response

  Involves T lymphocytes and only occurs in cells
• Humoral Response

  Involves B lymphocytes and occurs in liquids in the body
• How Self Cells are Recognised

  Lymphocytes are constantly colliding with cells. Some lymphocytes have receptors that are complimentary to self cells, these get suppressed or die. The only lymphocytes that remain are those that respond to non-self cells
• Apoptosis

  Programmed cell death that occurs when lymphocytes show an immune response to self-cells, this occurs before lymphocytes mature
• Phagocytosis


  The process by which a lymphocyte digests a pathogen and absorbs the useful nutrients into its cytoplasm
• Process of Phagocytosis

  Chemical products of the pathogen act as attractants, allowing phagocytes to move towards the pathogen. The receptors on the cell membrane attaches to chemicals on the surface of the pathogen. The phagocyte engulfs the pathogen and forms a phagosome. The lysosomes inside the phagocyte bind to the phagosome and release lysozyme to hydrolyse the pathogen. The phagocyte absorbs the useful products
• Lysozyme


  The enzyme that hydrolyses the pathogen enclosed by the phagosome
• Phagosome


  The vesicle inside the phagocyte that contains the pathogen
• Lysosome


  The small vesicle that contains lysozyme
• Antigens


  Unique glycoproteins on the surface of pathogens. The presence of these stimulates an immune response
• B Lymphocytes


  Produced in the bone marrow and mature in the bone marrow. Involved in the humoral response
• T Lymphocytes


  Produced in the bone marrow and mature in the thymus gland. Involved in the cellular response
• Cytotoxic T-Cells

  Produces perforin which makes holes in the antigen presenting cells, allowing the contents to leave the cell (ions and water)
• Helper T-Cells


  Simulates the phagocytosis of pathogens therefore multiply rapidly during the cellular response
• Memory T-Cells


  Remembers the specific shape of the antigen on the antigen presenting cells, this helps maintain immunity from that one specific pathogen
• Process of the Cellular Response

  T lymphocytes are complimentary to the specific shaped tertiary structure of the antigen, so they bind to one another, forming a sensitised T-Cell. This stimulates rapid mitotic division and differentiation into the three types of T-Cells
• Primary Immune Response

  Performed by plasma cells. They secrete 2000 antibodies per second. Only survive a few days but stimulate chemical destruction of the pathogen. This allows for antibody-antigen complexes to form
• Secondary Immune Response

  Performed by memory cells. They circulate in blood and tissue and recognise the antigens if they are presented again. This stimulates division of the memory cells to produce plasma for the primary immune response and more memory cells. This fast division allows the pathogen to be destroyed before it can harm the body.
• Process of the Humoral Response

  The B-Cell forms an attachment to the antigens, then undergoes processing where the pathogen is engulfed via endocytosis, allowing the B-Cell to present the antigens on its surface. Helper T-Cells bind to the processed B-Cells which stimulates mitotic division. Cloning then occurs to allow for the production of monoclonal antibodies. This allows for the primary and secondary immune response
• Variable Region

  Two regions on an antibody that has a specific shaped tertiary structure that can form antibody-antigen complexes. There are a minimum of two of these regions per antibody
• Constant Region

  Two regions on an antibody that is non-changing and is the same for all antigens
• 4

  The number of polypeptide chains making up an antibody. Half of which are short light polypeptide chains, the other half are long and heavy polypeptide chains
• Antibody

  Binds to antigens, causing agglutination and acts as a marker to stimulate a phagocyte
• Agglutination

  Where antibody-antigen complexes form and the antigen presenting cells get clumped up into one large area, rather than having the bacteria dispersed throughout the body
• Monoclonal Antibodies

  Many antibodies that come from the exact B-Cell when divided
• Uses of Monoclonal Antibodies

  Medical diagnosis, pregnancy testing
• Ethical Use of Monoclonal Antibodies

  Producing the antibodies involves using mice as a host. They have been used in clinical trials and some deaths associated with treating multiple sclerosis, however some success has come about from the use of the antibodies. Testing the safety of the drugs is also difficult as during one clinical trial, within minutes the volunteers suffered multiple organ failure due to T-Cells attacking self cells
• How Pregnancy Tests Work

  Monoclonal antibodies are present on the surface, they will agglutinate when forming an antibody-antigen complex with the hCG hormone. Producing a coloured line on the strip
• How Medical Diagnosis Works

  Agglutination would occur which would change the colour in the test if a specific disease is present that the monoclonal antibody is adapted to forming a complex with
• Monoclonal Antibody Therapy


  A type of treatment by which monoclonal antibodies are administered, the antibodies form an antibody-antigen complex with cancerous cells which prevents further growth and stimulates chemical destruction of the cancer