Topic 2C- Cells and the Immune System Part 3 Flashcards
What are monoclonal antibodies?
What does this mean that all monoclonal antibodies are?
Antibodies produced from a single group of genetically identical B-cells (plasma cells)
All monoclonal antibodies are identical in structure.
What is an example of targeting drugs to a particular cell type using antibodies?
What do different cells in the body have?
What are the antigens of cancer cells called?
What can be made to bind to these?
What can you also attach to these antibodies?
What do the antibodies do when they come into contact with the cancer cells?
What does this mean that the drug will only accumulate to?
What are the side effects of these drugs compared to other drugs and why?
Cancer cells
Different surface antigens
Tumour markers that are not found on normal body cells
Monoclonal antibodies can be made that will bind to the tumour markers
Anti-cancer drugs
They will bind to the tumour markers
Only accumulate in the body where there are cancer cells
The side effects of an antibody-based drug are lower than other drugs because they accumulate near specific cells.
What is an example of targeting a particular substance for medical diagnosis using antibodies?
What do these tests detect and where’s it found?
Describe stage one?
Describe stage two?
Describe stage three?
Describe stage four?
Describe stage five?
What happens if no hCG is present?
Pregnancy testing
The hormone Human Chorionic Gonadotropin (hCG) found in the urine of pregnant women
- The application area contains antibodies for hCG 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
- The test strip contains antibodies to hCG that are stuck in place (immobilised)
- If there is hCG present the test strip turns blue because the immobilised antibody binds to any hCG- concentrating the hCG-antibody complex with the blue beads attached.
The beads will pass through the test area without binding to anything, so it won’t turn blue.
What is the ELISA test?
What does the ELISA test stand for?
What two things does the ELISA test allow you to see?
What are two examples of the uses of ELISA test?
What is used in an ELISA test?
What can the enzyme then do?
What does this cause to the solution in the reaction vessel?
What does a colour change demonstrate?
How can the quantity of this antigen/antibody be worked out from in some types of ELISA tests?
A medical diagnostic test that uses antibodies
Enzyme-linked immunosorbent assay
- If a patient has any antibodies to a certain antigen
- If a patient has any antigens to a certain antibody
To test for pathogenic infections and allergies
An antibody is used which has an enzyme attached to it
The enzyme can react with a substrate to produce a coloured product
Causes the solution to change colour
That the antigen or antibody of interest is present in the sample being tested (eg blood plasma)
Worked out from the intensity of the colour change.
Describe a direct ELISA?
Describe an indirect ELISA?
Uses a single antibody that is complementary to the antigen you’ve been testing for
Different because it uses two different antibodies.
How can ELISA be used as a HIV test?
Describe stage one?
Describe stage two?
Describe stage three?
Describe stage four?
Describe stage five?
Describe stage six?
Describe stage seven?
An indirect ELISA test can be used to see if a patient possesses antibodies to the HIV virus
- HIV antigen is bound to the bottom of a well in a well plate (a plastic tray with loads of little circular pits in it)
- A sample of the patient’s blood plasma, which might contain several different antibodies, is added to the well
- If there are any HIV-specific antibodies (ie antibodies against HIV) these will bind to the HIV antigen stuck to the bottom of the well
- The well is then washed out to remove any unbound antibodies
- A secondary antibody, that has a specific enzyme attached to it, is added to the well. This secondary antibody can bind to the HIV-specific antibody (which is also called the primary antibody)
- The well is then washed out again to remove any unbound secondary antibodies. If there’s no primary antibody in the sample, all of the secondary antibody will be washed away
- A solution is added to the well. This solution contains a substrate, which is able to react with the enzyme attached to the secondary antibody and produce a coloured product.
What two things does the ELISA test for HIV indicate if it changes colour?
Why are the washing steps important?
What is an example of this?
Why would there be no colour change if the ELISA result was negative?
Describe the following ethical issues surrounding vaccines:
Testing on animals
Animals based substances
Risk of side effects
It indicates that the patient has HIV-specific antibodies in their blood and is infected with HIV
To make sure unbound antibodies aren’t left in the well which could affect the results
eg unbound secondary antibodies could cause the test to appear positive when there are no HIV antibodies present
Because there would be no HIV-specific antibodies for the secondary antibodies to bind to
All vaccines are tested on animals before being tested on humans
Animal based substances may be used to produce a vaccine
Some don’t won’t to take the vaccine due to the risk of side effects, but still protected due to herd immunity.
What is an example of testing vaccines on humans sometimes being tricky?
What do ethical issues surrounding monoclonal antibody therapy often include?
eg volunteers may put themselves at unnecessary risk of contracting the disease because they think they’re fully protected
Animal rights issues
Animals are used to produce the cells from which the monoclonal antibodies are produced.
