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Monoclonal antibodies

Monoclonal antibodies

  • Monoclonal antibodies: many identical antibodies.
  • These were invented for making large quantities of antibodies for identifying particular substances.
  • A lymphocyte can divide over and again to make identical clones of itself. However, once it starts making antibodies it becomes a B-lymphocyte and it can’t divide anymore.
  • To get around this problem a B-lymphocyte can be fused with a tumour cell (which divides very quickly) to produce a hybridoma.
    • Step 1: A mouse/rat is immunised by injection of antigen to stimulate the production of antibodies targeted against X.
    • Step 2: The antibody forming cells, B-lymphocytes, are isolated from the mouse’s blood.
    • Step 3: A tissue culture of tumour cells is grown.
    • Step 4: The B-lymphocytes and tumour cell are fused together which forms a hybridoma.
    • Step 5: Grown in a culture, to produce multiple hybridomas from the original one.
    • Step 6: The antibodies produce from the hybridomas are isolated and used later.

 

Using monoclonal antibodies

  • These are often used in medicine. An example is pregnancy testing. Antibodies are placed on a strip that bind with the hormone “human chorionic gonadotrophin” (hCG). This is found in the urine of women in the early stages of pregnancy.
  • The strip is dipped into some urine and if there is any hCG in it, it binds with the monoclonal antibodies on the strip and causes a colour change.
  • Monoclonal antibodies can be made radioactive to find cancer in the body.
  • Monoclonal antibodies can be developed in the lab to stick to the special substances found on cancerous cells and platelets. The antibodies are labelled with a radioactive element and then put in the patient. A picture of the patient’s body is then taken with a special camera that detects radioactivity.
  • Anywhere there are cancer cells or blood clots would show up as a bright spot as antibodies bind with the tumour markers on these cells.
  • This information can be interpreted by doctors to find where the cancer is, what size it is and how fast it is spreading.
  • Drugs can be attached to monoclonal antibodies to deliver the drug only to cells that need to be destroyed. This means less of the drug is needed, as none of it is wasted in parts of the body that are healthy. Healthy cells are much less of a risk of being harmed.