Monoclonal Antibodies


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•  Fusion of a tumor cell with an antibody-producing cell creates a hybridoma cell

•  Monoclonal antibodies are produced by hybridoma cells

Monoclonal antibodies are antibodies artificially derived from a single B cell clone (i.e. identical specific antibodies)

  • An animal (typically a mouse) is injected with an antigen and produces antigen-specific plasma cells
  • The plasma cells are removed and fused (hybridised) with tumor cells capable of endless divisions (immortal cell line)
  • The resulting hybridoma cell is capable of synthesising large quantities of monoclonal antibody

Production of Monoclonal Antibodies

monoclonal antibodies

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•  Monoclonal antibodies to hCG are used in pregnancy test kits

Monoclonal antibodies can be used for both the therapeutic treatment and clinical detection of disease

  • An example of therapeutic use involves the use of antibodies in the treatment of rabies
  • An example of diagnostic use involves the use of antibodies in the detection of pregnancy

Treatment Use

Monoclonal antibodies are commonly used to provide immune protection for individuals who contract harmful diseases

  • Because the rabies virus can potentially be fatal, injecting purified antibodies functions as an effective emergency treatment
  • Monoclonal antibodies can be used to target cancer cells that the body’s own immune cells fail to recognise as harmful

Therapeutic monoclonal antibodies are named according to the source organism from which the antibodies were derived

  • Mice antibodies ('-omab’) are easier to synthesise than human antibodies but are less likely to be tolerated by the patient

Examples of Therapeutic Monoclonal Antibodies

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Diagnostic Use

Monoclonal antibodies can be used to test for pregnancy via the presence of human chorionic gonadotrophin (hCG) in urine

  • hCG is a hormone produced by women during foetal development and thus its presence in urine is indicative of pregnancy

Pregnancy tests use a process called ELISA (enzyme-linked immunosorbent assay) to identify a substance via a colour change

  • Free monoclonal antibodies specific to hCG are conjugated to an enzyme that changes the colour of a dye
  • A second set of monoclonal antibodies specific to hCG are immobilised to the dye substrate
  • If hCG is present in urine, it will interact with both sets of monoclonal antibody (forming an antibody ‘sandwich’)
  • When both sets of antibody are bound to hCG, the enzyme is brought into physicial proximity with the dye, changing its colour
  • A third set of monoclonal antibodies will bind any unattached enzyme-linked antibodies, functioning as a control

How a Pregnancy Detection Kit Works

                 Pregnancy Tests:             Kit Components                 Positive Result                  Negative Result