Monoclonal antibodies can be used in the treatment of cancer. Explain how monoclonal antibodies are produced and how they can be used to treat cancer patients.

WJEC A-Level Biology (Wales) — 3.2 Respiration · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (5 marks)

1. A specific antigen is injected into an animal (e.g. a mouse) to trigger an immune response.
2. Lymphocytes that recognise the antigen are isolated from the animal.
3. These lymphocytes are fused with tumour cells to form hybridoma cells; the hybridomas can divide indefinitely and secrete identical (monoclonal) antibodies.
4. The monoclonal antibodies are selected so that they bind to antigens expressed on the surface of specific cancer cells.
5. The antibodies are conjugated to chemotherapy drugs (or radioisotopes) so that, when they bind the cancer cells, the drug is delivered directly to the tumour, sparing normal tissue.

Examiner tips

  • Use the word ‘fused’ when describing hybridoma formation; examiners look for this term. Show the full sequence: antigen → immune response → lymphocyte isolation → fusion → hybridoma → monoclonal antibody. Mention that the antibody is conjugated to a drug to achieve targeted delivery.
  • common_mistakes
  • :
  • Failing to state that lymphocytes are fused with tumour cells to create hybridomas. Using ‘antibody’ instead of ‘monoclonal antibody’. Omitting the step that the antibody is conjugated to a chemotherapy drug for targeted delivery.

Mark scheme (5 marks)

  1. A specific antigen is injected into an animal (e.g. a mouse) to trigger an immune response
  2. Lymphocyte cells are taken from the animal / lymphocytes produce antibodies complementary to the antigen
  3. Lymphocyte cells are fused with tumour cells to make hybridoma cells, which can divide continuously and produce monoclonal antibodies
  4. Monoclonal antibodies are made to bind to antigens on specific cancer cells
  5. The monoclonal antibodies carry chemotherapy drugs directly to the cancer cells, targeting them specifically

Key terms in this question

monoclonal antibodies

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