Monoclonal antibodies

Monoclonal antibodies are identical antibodies that recognise one specific epitope.

Production:

First an antigen is injected into a host organism (e.g. rabbit or mouse). The hosts immune system will the start to produce antibodies against the antigen. To see if the desired antibody has been produced a blood sample of the model organism is then taken-if positive the spleen is removed.

The B-cells in the spleen producing the antibodies are released by being placed in a certain medium. However, the B-cells are unable to survive outside of the host organism very well. To overcome this problem the B-cells are fused with Myeloma cells (a malignant cancer) producing Hybridoma cells which can rapidly divide and continue to produce the antibodies. The Hybridoma cells are individually separated out and grown in culture. The cultures will now contain identical cells all producing a single immunoglobulin in each generation. All the antibodies produced in the culture are the same and are monoclonal antibodies.

Uses:

Pregnancy testing:

Monoclonal antibodies bind to a specific hormone (hCG) which is released after conception. The monoclonal antibody is usually coated in a substance which is able to change colour depending if the antigen-antibody complex has been formed.

Anticancer treatments:

Monoclonal antibodies can be made to specifically recognise cancer cells. The genes encoding specific antibody subunits are cloned, and the area encoding the antigen-binding region is combined with human DNA sequences encoding the rest of the antibody to produce a humanised monoclonal antibody. Anticancer drugs can be bound to the antibody and released when the antigen-antibody complex has formed. This allows the treatment to directly target the cancer cells and not harm the other healthy cells.