Pack 6 Cell recognition and the immune system Part 2

Pack 6 Cell recognition and the immune system Part 2

1. Monoclonal antibodies

   • Antibodies that are produced by a single clone of B cells
   • Method:
     • 1. Mice are injected by non-self material against which an antibody is required
       • 2. B cells in the mouse produce a mixture of antibodies, these B cells are extracted from the spleen of the mouse
         • 3. B cells are fused with cells that last a long time (a bone cancer cell is used)
           • 4. Fused cells (hybridomas) are grown individually in tissue cultures
             • 5. Any clone producing the correct antibody is grown on a large scale
   • Uses:
     • Targeting medication
       • Direct monoclonal antibody therapy
         • A monoclonal antibody is produced that is specific to an antigen
           • Antibodies are given to the patient and attach to the receptors on (for example) a cancer cell
             • The attachment blocks chemical signals that stimulate uncontrolled growth
       • Indirect monoclonal antibody therapy
         • Same as direct but adds a radioactive or cytotoxic drug to kill the cell
     • Medical diagnosis
       • ELISA:
         • 1. Test sample antigens are attached to a well in a test dish
           • 2. Unattached antigens are washed off
             • This will stop antibodies attaching to any unattached antigens
             • 3. Antibody to the antigen to be detected is added
               • 4. Excess antibody is washed off
                 • If they aren't bound but still in the sample you will get a false positive result
                 • 5. A second antibody that only binds with the first and has an enzyme attached is added
                   • 6. Excess antibody is washed off
                     • 7. Colourless substrate to the enzyme is added
                       • 8. the enzyme will act on the substrate to form a coloured product if present

2. HIV

   • HIV directly attacks cells such as T helper cells that have a protein called CD4 on their surface
     • HIV infected cells die after released the replicated virus which then infect other T helper cells
       • This means B cells won't be stimulated to produce antibodies