Lecture 45

Question 1

B cells are activated by what two signals?

Answer 1

• Thelper cell cytokines
• native antigen
• —> B cell differentiates into plasma cell which secretes antibodies
• —-> differentiates into B memory cells

Question 2

What are the three functions of antibodies?

Answer 2

1) Neutralisation
- —> binds to host cells and neutralises virus
2) Opsonisation
3) Complement activation

Question 3

B cells develop & mature in bone marrow where they undergo genetic rearrangement this means that they:

Answer 3

• recognise a great diversity of antigens
• each express a unique antigen receptor - BCR
• —>recognition of a wide range of antigens
• after genetic rearrangement they can secrete antibodies

Question 4

What is the B cell receptor BCR structure?

Answer 4

• two identical heavy chains
• two identical light chains
• disulfide bonds link chains together
• variable regions which vary btw B cells due to genetic rearrangement in bone marrow
• surface is covered with IgM/IgG

Question 5

What do B cell receptors do?

Answer 5

bind native antigen and activates B cell differentiation into plasma cells and memory B cells
- needs Th and native antigen to bcm activated

Question 6

What is isotope switching?

Answer 6

• B cells can change a portion of their heavy chain

- —> gives the antibody new properties

Question 7

What is the role of IgE in drug reactions?

Answer 7

• Penicillin is highly reactive and modifies self-proteins
  —> makes things look foreign & t cells will attack it
  IgE responds to penicillin-modified proteins