Monoclonal Antibodies

Question 1

What are monoclonal antibodies?

Answer 1

antibodies produced from a single group of genetically identical B-cells so they are all identical in structure

Question 2

Why are monoclonal antibodies useful?

Answer 2

useful in dealing with antigens as they can be made to bind to anything

Question 3

How can direct monoclonal antibody therapy target cancer cells?

Answer 3

• some cancer can be treated using monoclonal antibodies which are designed with a binding site complementary to the antigens on the cancer cells (wont harm normal body cells as it can only attach to cancer cells)
• while the antibodies are bound to the cancer antigens it prevents chemicals binding to the cancer cells which enable uncontrolled division

Question 4

How can indirect monoclonal antibody therapy target cancer cells?

Answer 4

anticancer drugs can be attached to those antibodies which are delivered directly to the cancer cells and kill them which reduces the harmful side effects compared to chemotherapy/radiotherapy as they accumulate near specific cells

Question 5

Ho ware monoclonal antibodies used for diagnosis?

Answer 5

• test for pregnancy, HIV, prostate cancer
• works via an ELISA test

Question 6

What are ELISA tests?

Answer 6

used to see if a patient has ay certain antibodies to a certain antigen or certain antigen to an antibody
1.) an enzyme is attached to antibodies
2.) when this enzyme reacts with a certain substrate, a coloured product is formed causing the solution in the reaction vessel to change colour
3..) if a colour change occurs the antigen/ antibody is present

Question 7

What is a direct ELISA test?

Answer 7

single antibody is used that is complementary to antigen being tested

Question 8

What is an indirect ELISA test?

Answer 8

two different antibodies (known as primary and secondary) are used

Question 9

What is the process of a direct ELISA test?

Answer 9

1.) Antigens are attached to test plate
2.) sample being tested is passed over the test plate and if the antibodies are present they will bind to the antigen
3.)plate is washed to get rid of any sample that is not attached
4.) a monoclonal antibody with an enzyme attached is then passed over the plate and if the original antibody is present it will bind to it. + wash again
5.) A dye called chromagen is passed over the plate and the enzyme catalyses a colour change in the dye substrate - the more intense the colour, the more antibodies present

Question 10

What happens if the test plate is not rinsed properly in an ELISA test?

Answer 10

you can get a false positive as the enzyme will remain even if it has not bound so a colour change may still occur

Question 11

What is the procedure of an indirect ELISA test testing for antigens?

Answer 11

1.)Antibodies specific to the antigen are bound to the bottom of the reaction vessel
2.) blood sample is added and antigens bind to the primary antibody + wash
3.) a secondary antibody with an enzyme attached is added and will only bind to primary antibody is specific antigen is present
4.) substrate added and enzyme reacts with substrate forming a coloured product

Question 12

What is the procedure for an indirect ELISA test testing for antibodies?

Answer 12

1.) antigen bound to bottom of reaction vessel
2.) blood sample is added and antibodies specific to the antigen will bind
3.)wash to remove unbound antibodies
4.) secondary antibody with attached enzyme is added + wash out
5.) substrate added (enzyme reacts with substrate forming a coloured product- colour change=antibody present)

Question 13

How are monoclonal antibodies produced?

Answer 13

1.) mouse is injected with specific pathogen –> mouses immune system responds
2a.) specific white blood cells (B Lymphocytes) produce antibodies
2b.) tumour cells are able to divide but cant make antibodies
3.) B cells are combined with tumour cells - these cells are now called hybridoma cells and make specific antibodies –> screened to make sure they produce the right one
4.) the hybridoma cells copy themselves and produce antibodies (monoclonal antibodies as they come from once cell)

Question 14

How can monoclonal antibodies be sued to treat cancer?

Answer 14

• once monoclonal antibodies bind to cancer cells they trigger white blood cells to attack and destroy
• some bind to antigens on cancer cells which prevents attachment of chemical that causes uncontrolled division
• some carry toxic drugs/ radioactive drugs that bind to and kill cancer cells

Question 15

What are the ethical issues of monoclonal antibodies?

Answer 15

• use of animals (mice)

Question 16

How can monoclonal antibodies be used to locate blood clots?

Answer 16

1.) inject a mouse with human fibrin (the protein found in blood clots)
2.)this activates the plasma cells to produce antibodies against fibrin
3.) these cells are collected from the mouse spleen
4.) the plasma cells are then fused with tumour cells forming hybridomas that produce antifibrin antibodies
5.) to detect where the antibodies are binding to fibrin molecules, a radioactive chemical (producing gamma radiation ) is attached to the antibodies making them radioactively labelled
6.) a gamma ray camera is used to detect where these radioactively labelled antibodies have attached to a fibrin molecule therefore showing where blood clots can be found