monoclonal antibodies and ELISA tests

Question 1

monoclonal antibodies

Answer 1

-antibodies made from a single group of genetically identical B plasma cells
-all identical structure
-antibodies are specific
-can make monoclonal antibodies bind to anything you want

Question 2

detection (pregnancy tests)

Answer 2

-they detect the hCG found in the urine of pregnant women
-the test has antibodies for hCG which is bound to a dye activating enzymes
-when urine is applied, hCG will bind with the antibody on the enzyme forming an antigen-antibody complex
-the urine moves up the stick to the test strip carrying complexes with it
-the test strip contains antibodies to hCG that are immobilised
-if there is any hCG present the test strip turns blue because the immobilised antibody binds to hCG (concentrating the hCG-antibody complex with attached dye activating enzyme)
-if no hCG is present, then the complexes will pass through the test area without binding

Question 3

diagnosis- ELISA tests (immunoassays)

Answer 3

-enzyme linked…. antibody
-monoclonal antibodies are linked to enzymes
-the enzyme substrate is added resulting in a subsequent reaction reducing a detectable signals, most commonly a colour change in the substrate

Question 4

direct ELISA test

Answer 4

• uses a single antibody that is complimentary to the antigen
  -malaria, take blood sample containing antigens
  -put into wells of a plate and it sticks
• antibodies to the malaria antigens are added (have an enzyme on them)
  -substrate is added, colour change is seen

Question 5

sandwich ELISA tests

Answer 5

-looks for the antigen in the serum
-the wells have bound antigens
-the serum has the antigen
-then a secondary antibody binds to the complex
-the second antibody generate the signal with the enzyme its linked to

Question 6

indirect ELISA tests

Answer 6

-uses two different antibodies
-the enzyme is linked to an antibody of an antibody

Question 7

monitoring

Answer 7

-can use ELISA tests to show concentrations of proteins or chemicals in the blood
-used to detect blood doping in athletes

Question 8

cancer treatment

Answer 8

-monoclonal antibodies as chemical signal to trigger the phagocytes to engulf target cells
-using monoclonal antibodies to block receptors on the surface of cancer cells and stops cells from growing and dividing
-using monoclonal antibodies to carry cancer drugs directly to the cancer cells

Question 9

treating cancer cells

Answer 9

-cancer cells have antigens called tumour markers which are different to normal body cells
-monoclonal antibodies can be made to bind to tumour markers
-you can attach anti-cancer drugs to the antibodies
-when the antibodies come into contact with the cancer cells they bind to the tumour markers
-the drug will only accumulate in the body where there are cancer cells
-the side effects of antibody based drugs are lower than other drugs because they accumulate near specific cells

Question 10

herceptin

Answer 10

blocks receptors on breast cancer cells and slows growth

Question 11

ethics

Answer 11

-use of animals to form antibodies and cancer cells
-genetic engineering is used to humanise the antibody and this raises the whole debate over genetic engineering
-why not use humans to inject antigens and extract antibodies from them
-they have been used to treat some cancers successfully and diabetes but have been deaths related to multiple sclerosis sufferers
-march 2006, 6 volunteers had an adverse effect from a new monoclonal antibody drug