Antibodies

Question 1

What is the definition of an antibody?

Answer 1

• An antibody is a protein with a specific binding site which is synthesised by B cells

Question 2

What is the structure of an antibody?

Answer 2

• Antibodies are made of four polypeptide chains
• the chains of one pair are long and called heavy chains
• the chains of the shorter pair are called light chains
• each antibody has a specific binding site that fits precisely onto the foreign antigen, known as the antigen - antibody complex
• each antibody also has a variable reigon where the binding site differs

Question 3

How do antibodies lead to the destruction of antigens

Answer 3

• when an antigen is a bacterial cell, antibodies lead to agglutination of bacterial cells
• this allows them to act as markers for phagocytes
• other methods include: inflammation, precipitation, neutralisation and complement

Question 4

What is a monoclonal antibody?

Answer 4

• ​Identical antibodies that have been produced by an immune cell that has been cloned from a parent cell.

Question 5

What are the different uses of monoclonal antibodies?

Answer 5

• direct monoclonal antibody therapy and indirect monoclonal antibody therapy (used to treat cancer)
• medical diagnosis
• pregnancy testing

Question 6

What is direct monoclonal antibody therapy?

Answer 6

• Monoclonal antibodies are very specific to a specific antigen and can be used to target specific substances and cells
• monoclonal antibodies can be produced to be specific to antigens on cancer cells
• These antibodies are given to a paitent and they attach themselves to receptors on cancer cells
• this blocks the cancer cells from releasing chemical signals that stimulate their uncontrolled growth
• An example of this is hercept used for breast cancer

Question 7

What is an advantage for direct monoclonal antibody therapy?

Answer 7

• An advantage is that it is not toxic and is highly specific, which can lead to fewer side effects

Question 8

What is indirect monoclonal antibody therapy?

Answer 8

• This involves attaching a radioactive cytotoxic drug to an antibody so that when it attaches to a cancer cell, it kills them

Question 9

How are monoclonal antibodies used in medical diagnosis?

Answer 9

• monoclonal antibodies are used in diagnosing diseases such as influenza, chlamydia and cancer
• they can also diagnose diseases such as prostate cancer
• this is because monoclonal antibodies bind to antigens released by pathogens and can therefore give a positive test.

Question 10

How are monoclonal antibodies used in pregnancy testing?

Answer 10

• Monoclonal antibodies are used in pregnancy testing and can be used to determine levels of the hormone HCG in mothers urine
• Monoclonal antibodies are present on the test strip and are linked to colour particles
• If HCG is present, the urine will bind to the antibodies and form a HCG-antibody- colour complex which will move and produce a positive test

Question 11

Name three ethical issues with monoclonal antibodies?

Answer 11

1. the production of monoclonal antibodies involves the usage of mice. Mice are therefore intentionally given cancer to produce tumour cells and complementary antibodies to it.
2. There have been deaths and unknown side effects in paitents
3. When testing on humans, all 6 volunteers suffered multiple organ failures. Whilst all survived testing and drug trails, it can be dangerous

Question 12

Give another example of the use of monoclonal antibodies?

Answer 12

• cancer cells have tumour markers