2: CELLS - MONOCLONAL ANTIBODIES + ELISA TESTS Flashcards
What are monoclonal antibodies?
antibodies produced from a single group of genetically identical B-cells (plasma cells)
How are monoclonal antibodies produced in a lab?
- mouse injected with pathogen
- mouse produces B-lymphocytes which produce antibodies specific to the antigen
- mouse B-lymphocytes removed/isolated
- B-lymphocytes fused with tumor cells to form hybridoma cells
- hybridoma cells divide rapidly by mitosis forming many plasma cells
- plasma cells produce large amounts of the specific antibody
- antibodies collected and purified
What are some uses of monoclonal antibodies?
- medical treatment (eg: magic bullets)
- diagnosis (eg: pregnancy tests, lateral flow tests)
What are magic bullets?
monoclonal antibodies with a drug attached
Explain how monoclonal antibodies can be used in cancer treatment and the benefit of this
- anti-cancer drugs can be attached to monoclonal antibodies
- when the antibodies come into contact with the cancer cells, they will bind to the tumor markers (antigens on tumor cells)
- this means that the drug will accumulate in the body where there are cancer cells which minimises damage to normal body cells
How are monoclonal antibodies used in pregnancy tests?
- application area contains monoclonal antibodies that are complementary to the hCG protein, bound to a coloured bead (blue)
- when urine is applied to the application area, any hCG will bind to the antibody on the beads forming an antigen-antibody complex
- the urine moves up the stick to the test strip carrying any beads with it
- if hCG is present, the test strip turns blue because the immobilised antibodies on the test strip bind to the hCG concentrating hCG-antibody complex with the blue beads attached
- if hCG is not present the beads pass through the test area without binding to anything so it won’t go blue
What is an ELISA test and what are they used for?
- an ELISA test is a test for antigens to a certain antibody/antibodies to a certain antigen
- used to test for pathogenic infections (eg: HIV), allergies (eg: nut allergies), etc.
What does direct ELISA test for?
test to see if a patient has antigens to a certain antibody
Describe the process of direct ELISA
- antigens from a patient sample bound to a well in a well plate
- a detection antibody (with an attached enzyme) that is complementary to the antigen of interest is added. if the antigen of interest is present in the patient sample, it will be immobilised on the inside surface of the well and the antibody will bind to it
- the well is then washed out to remove any unbound antibody and a substrate solution is added
- if the detection antibody is present the enzyme reacts with the substrate to produce a coloured product causing the solution to change colour, showing a +ve result
What does indirect ELISA test for?
test to see if a patient has antibodies for a certain antigen
Describe how indirect ELISA can be used to test if a patient has HIV
- HIV antigen bound to a well in a well plate
- a sample of the patient’s blood plasma which may contain several different antibodies is added to the well. if there are any HIV-specific antibodies, they will bind to the HIV antigen stuck to the bottom of the well
- the well is washed out to remove any unbound antibodies
- a secondary antibody with an enzyme attached is added. this secondary antibody can bind to the HIV-specific antibody
- the well is washed out again to remove any unbound secondary antibody
- a solution containing a substrate is added. the substrate reacts with the enzyme to produce a coloured product. if the solution changes colour, it indicates that the patient has HIV-specific antibodies in their blood and therefore is infected with HIV
What are the ethical issues around monoclonal antibodies?
- animal rights issues
- animals (eg: mice) are used to produce cells from which monoclonal antibodies are produced which some people disagree with
