Monoclonal AB

Question 1

Describe the structure of an antibody

Answer 1

.\ /./

Question 2

What is “clonal selection”?

Answer 2

Cells - have Ab complement Ag => triggered to proliferate => Plasma & memory cells

Question 3

What are “Specificity” and “Cross-reactivity” in relation to

antibodies?

Answer 3

• Specificity: ability of Ab to distinguish Ag (when there’s great difference in affinity)
• Cross-reactivity: cross-reaction of Ab to unrelated Ag w/ structural similarities in epitope - can bind even though interaction is not strong)

Question 4

How are specificity and cross-reactivity related?

Answer 4

specify decreases as cross-reactivity increase (bc specificity of Ab may not be absolute => can cross react)

Question 5

What is the difference between a monoclonal antibody and a polyclonal antibody?

Answer 5

• Mono: Ab - directed to 1 epitope (v specific)

- Poly: Ab - directed to a number of epitopes (less specific)

Question 6

Briefly outline how monoclonal antibodies are produced.

Answer 6

1. infect animal w/ antigen
2. remove spleen & take B cells
3. Mix B cells w/ myeloma cells (cancer cells = always proliferating) & PEG => get hybridoma (B cell x myeloma cells)
4. remove PEG & screen cells that are producing Ab to Ag
5. Culture cells & freeze

Question 7

What is a “Hybridoma”

Answer 7

cell that has been created due to fusion of 2 cells (e.g. B cell / myeloma cells = endless supply of Ab)

Question 8

How is hybridoma selected for?

Answer 8

Grow mixed cells on HAT media

• Hypoxanthine & thymine for salvage pathway - myeloma cells can’t use bc lack HGPRT (≠ nucleotides made)
• Aminopterin inhibit de novo pathway (≠ nucleotides made)
• B cells will die bc mortal & Myeloma cells die bc lack HGPRT => hybridomas grow (immortal supply of Ab)

Question 9

Give 3 uses for monoclonal antibodies.

Answer 9

• used as 1º Ab in ELISA, RIA, Western blott, flow cytometry & IHC
• detect tumour Ag, CD marker ID on WBC, detect bacteria/virus

Question 10

What is a “humanised” monoclonal antibody?

Answer 10

monoclonal of animal attached to Fc of human

Question 11

What is Rituximab and describe what is it used for.

Answer 11

a) chimeric monoclonal Ab (…mab) directed against CD20 (on B cells)
b) used to remove B cells: in B cell lymphomas, transplant rejection, leukaemia, Autoimmune disorders (RA)

Question 12

difference b/w paratope & epitope

Answer 12

• paratope: Ag-binding site (on variable region of Ab)

- Eptiope Ag.enic determinant on Ag