Immunology - 23

Question 1

Which are the two ways in which B cell activation can occur?

Answer 1

• T dependent activation

* T independent activation (we are not going to discuss it)

Question 2

Do naïve B cells have to receive additional signals from CD4+ T cells (T helper cells) to become activated?

Answer 2

Yes, most of the time

Question 3

What are the two signals to activate a T dependent antigen?

Answer 3

Signal 1: antigen-BCR (sent to nucleus. Once this occurs it is primed)
Signal 2: CD40 on primed B cell interacts with CD40L unactivated T helper cell

B cell becomes fully activated

Question 4

What is the CD4+ T cells side of the story for T cell dependent activation?

Answer 4

1 - an AEPC phagocytosis the pathogen, processes it and presents peptides on MHC Class II
2 - CD4+ T cells bind and the T cell becomes activated

Question 5

Activated B cells (plasma cells) make clones of themselves. During this clonal proliferation stage the daughter B cell undergoes what?

Answer 5

Somatic hyper mutation (affinity maturation) and isotype switching

Question 6

Which are short-lived and which are long-lived (plasma cells versus memory B cells)?

Answer 6

• Plasma cells - short-lived and terminally differentiated

* memory B cells - long-lived and not terminally differentiated

Question 7

When do memory cells become activated again?

Answer 7

When they encounter antigen

Question 8

What happens to activated memory B cells?

Answer 8

They migrate to a lymph node to undergo the same changes as any activated B cell:
1 - clonal expansion
2 - undergo affinity maturation
3 - class which
4 - career decide

Question 9

Which are the checkpoints in the development of a B cell?

Answer 9

• Heavy chain rearrangement
• Light chain rearrangement
• negative selection