Defence against Diseases - Monoclonal antibodies Flashcards
what are monoclonal antibodies and how do they work
- identical antibodies that are all produced from a single clone of cells, formed from one specific B-Lymphocyte
- mAB’s are specific to one binding site on one protein antigen + complementary to shape of antigen –> can target a specific chemical or specific cell in the body
describe the stages in which mAB’s are produced
- mouse is injected with the specific antigen that the scientists want to produce antibodies to
- B-Lymphocytes in mouse are stimulated and produce antibodies to the antigen
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B-Lymphocytes are extracted from mouse
4 . B-Lymphocytes are combined with a tumour cell : by adding a detergent to cells to make the cell surface membranes of both the B-Lymphocyte an tumour cell fuse together - the combining of B-Lymphocyte and tumour cell forms a HYBRIDOMA CELL
- the hybridoma cell has 2 important characteristics
- can divide repeatedly to produce genetically identical cells (characteristics of tumour cells)
- can produce the desired specific antibody
- hybridoma cells is then cloned : divides repeatedly making genetically identical copies of itself
- each cloned hybridoma cells produces the specific antibodies to the antigen
- the antigens are collected + purified
advantages of mABs
- can target any molecule, including humans
- don’t kill adjacent cells, unlike some anti-cancer drugs
- can be produced in huge quantities, quickly
what can mABs be used in
- Diagnostic tests - pregnancy tests
- measure hormone levels
- detect pathogens in blood
- locate / identify specific molecules in a cell / tissue by binding to them with fluorescent dye
- treat some diseases - cancer –> mABs bind to a radioactive substance, toxic drug / chemical which stops cell growth + division –> delivers the substance to the cancer cells without harming other cells in body
disadvantages of mAB’s
- can create more side effects than expected
- are not as widely used as everyone hoped when they were first developed
what hormone is found in pregnant women
HCG
how do pregnancy kits work
- sipstick dippled in early morning urine sample
- dipstick contains mAB specific for hCG which are mobile
- mAB have blue dye particle attached (dye- mAB)
- hCG in urine moves up the strip
- hCG acts as antigen
- hCG binds to dye-mAB due to complementary shapes of the hCG to the binding site of the mAB
what does the 1st test window show
the test result - coloured line = pregnancy
what does the 2nd window show
if the test is working
what process happens at the 1st window
- a second mAB specific for the hCG-dye-mAB complex is immobilised in a test window
- 1st hCG-dye-mAB complex binds to 2nd mAB –> help in position
- blue dye accumulates
- coloured lined indicates pregnancy
what happens at the 2nd test window
- any uncombined antibodies dye-mAB continue to move up the dipstck
- to a 2nd line of mAB specific antibodies
- to form a second coloured band that shows strip is working
why are women advised to test with urine after they first wake up after a nights sleep
concentration of hCG will be higher –> test more accurate + reliable
what antigen is present in prostate cancer
PSA (prostate specific antigeb)
describe the blood test for PSA using monoclonal antibodies
- Antibodies to PSA bound to bottom of the reaction vessel
- blood plasma sample added –> PSA binds to primary antibody
- Wash out ( removes any unbound antigens)
- Secondary antibody (antibody + enzyme) added –> only binds to Primary antibody if PSA is present
- Wash out–> removes any unbound antibodies
- substrate added –> enzyme reacts with substrate, forming a coloured product
- if enzymes did not bind to primary antibody (PSA not present), then will be rinsed out –> substrate will not react with enzyme –> to colour change –> PSA not present