Practical uses of Antibodies

Question 1

What are antibodies / immunoglobulins?

Answer 1

Glycoproteins produced in response to invading foreign particles

Question 2

What is an epitope?

Answer 2

A particular molecular structure on the surface antigen.

Question 3

How can you create a phage library to find antibodies?

Answer 3

1. harvest b cells
2. clone antibody binding regions (FAB area)
3. put into bacteriophage as a fusion gene
4. will produce phage particle that have bits of the antibody in its surface
5. make phage library and can then see which antibody binds to which antigen

Question 4

How do pregnancy tests work?

Answer 4

Pregnancy tests rely on monoclonal antibodies which bind to human chorionic gonadotrophin (hCG) which is made in early stages of pregnancy. Tine amount of the hormone are passed out of the body in the urine.

Question 5

How can monoclonal antibodies be used as a diagnostic tool for diseases?

Answer 5

• they can be made which to bind to specific antigens on cells (cancer cells)
• used to recognise proteins in the blood

Question 6

How can monoclonal antibodies be used as a treatment tool for diseases?

Answer 6

• they can be used to carry drugs to specific tissues because they bind to the antigens in a tumour
  (e. g. drugs or radioactive substances directly to the cancer cells)

Question 7

How does flow cytometry work?

Answer 7

1. have a bunch of cells (could be leucocytes)
2. incubate with fluorescent tagged antibody that binds to a specific epitope
3. wash away the antibodies so only the cells that have the epitope required have a bound antibody attached
4. analyse by microscopy or FACS
   (FACS will separate the fluorescent cells onto separate populations)

Question 8

How can you use monoclonal antibodies to diagnose different disease settings?

Answer 8

• use clinical features
• look at the patterns of fluorescence intensity after FACS, certain disease states will see a high expressions of positive antibodies

Question 9

How are autoantibodies detected using monoclonal antibodies?

Answer 9

Usually by an analysis of the interaction of patient serum with the target tissue.
- can use monoclonal anti-Igs

Question 10

How can blood groupings be tested for using monoclonal antibodies?

Answer 10

• seeing which antibodies bind to the antigens present in A/B/AB/O
• detecting rhesus antigens
  (exposure of rhesus negative mother to rhesus positive infant can result in the production of antibody which traverses the placenta and causes haemolytic diseases in the newborn)

Question 11

What bacterial infections can monoclonal antibodies be used to confirm the identities for?

Answer 11

Neisseria gonorrhoea and other Neisseria species

Question 12

How can analytes be recognised on beads? - chemical pathology

Answer 12

1. start of with range of nano particle beads
   - have different amounts of fluorochrome
   - monoclonal antibodies have been coated onto the capture beads
2. sample is added and incubated to allow the antibody-coated capture beads to bind the analytes
3. detector antibodies against the analytes of interest, labelled with a fluorochrome that is different from the fluorochrome in the capture beads
4. The different analytes can be quantified by looking at the intensity of the capture bead fluorescence. The amount of the analyte can be measure by the second fluorochrome (the ones on the detector antibody)

Question 13

How can monoclonal antibodies be used in tissue pathology?

Answer 13

• add fluorescent labels onto antibodies and bind them to tissues
• can put it on antibodies that will bind to normal tissue and so the lack of binding will show cancerous effects (such as the basal layer in prostate tissue in prostate cancer)