Monoclonal antibodies & ELISA

Question 1

Uses of monoclonal antibodies?

Answer 1

• Targeting medication to specific cell types - direct & indirect monoclonal antibody therapy
• Medical testing
• Medical diagnosis using ELISA

Question 2

Direct monoclonal antibody therapy?

Answer 2

• Monoclonal antibodies are produced specific to the antigens on the target cells (eg. cancerous cells)
• antibodies are given to a patient
• antibodies attach to the antigens on the surface of the target cells & prevent their uncontrolled growth (by blocking signalling pathways in them aka prevent chemicals that enable uncontrollable cell div from binding)
• adv: doesn’t harm healthy cells

Question 3

Indirect monoclonal antibody therapy?

Answer 3

• A cytotoxic drug (a drug that kills cells) is attached to the monoclonal antibodies
• antibodies are given to the patient
• when the antibodies attach to the antigens on the target cells it kills the cells
• adv: better than chemo & radio therapy

Question 4

Medical testing e.g. Pregnancy test?

Answer 4

If pregnant:
- urine absorbed onto strip & moves along test
- Reaction site: mobile anti-HCG antibody complementary to HCG (antibody has enzyme/coloured dye attached)
- Test site: fixed/immobile anti-HCG antibody (hormone will bind to immobilised w 1st antibody w dye still attached so - 1st antibody w dye stays in that pos so - line)
- Control site - fixed/immobile antibodies complementary to unbound antibodies (so alw get band if test is working)
Not pregnant:
- mobile antibody move all way along

Question 5

Medical diagnosis using ELISA?

Answer 5

1. Add test sample from patient to base of beaker
2. wash to remove any unbound test sample
3. add an antibody complementary to antigen ur testing the presence of in the sample
4. wash to remove any unbound antibody
5. add a 2nd antibody that is complementary in shape to 1st antibody & binds to it - 2nd antibody has enzyme attached
6. substrate for (colourless) enzyme is added - substrate produces coloured products in presence of enzyme
7. presence of colour indicates presence of antigen/intensity indicates quantity

Question 6

Why do a control test for ELISA?

Answer 6

To check only the presence of the enzyme is causing the colour change

To check that the washing out of the wells is effective

Question 7

Ethical issues of monoclonal antibodies?

Answer 7

• Mice used to produce both the monoclonal antibodies and the tumour cells - involves deliberately inducing cancer in mice (animal cruelty)
• deaths
• risks
• testing the safety of new drugs in trials can be dangerous
• Maybe drug trials should be limited to volunteers who are terminally ill with a condition that the monoclonal antibody is designed to treat?