CH. 9: B Cell Development and Activation

Question 1

stem > pro-b > pre-b > immature > mature > memory or plasma

Describe what happens during the pro-b cell stage. Which CD markers are expressed?

Answer 1

• 1st rearrangement of Ig heavy chain gene (D rearranges to J)
• expresses CD10, CD19

Question 2

stem > pro-b > pre-b > immature > mature > memory or plasma

Describe what happens during the pre-b cell stage. Which CD markers are expressed?

Answer 2

• 2nd rearrangement of Ig heavy chain gene (DJ segments join with V)
• synthesis of mu-chain (Ig-alpha/beta)
• express CD10, CD19
• pre-BCR is the important checkpoint
• light chain rearrangement begins at the end

Question 3

stem > pro-b > pre-b > immature > mature > memory or plasma

Describe what happens during the immature b cell stage. Which CD markers and Ig are expressed?

Answer 3

• light chains pair with mu-chains to form monomeric IgM
• expresses CD19, CD20 and BCR
• may express IgM specific for foreign antigen or self antigen (negative selection)

Question 4

stem > pro-b > pre-b > immature > mature > memory or plasma

Describe what happens during the mature b cell stage. Which CD markers and Ig are expressed?

Answer 4

• may not have been introduced to antigen (naive B cell)
• IgM and IgD is expressed
• expression of CD19, CD20

Question 5

stem > pro-b > pre-b > immature > mature > memory or plasma

Describe what happens during the plasma cell stage. Which CD markers and Ig are expressed?

Answer 5

• responds to t-dependent antigens
• no membrane expression
• secretes IgM (or other IgG, IgA, or IgE after isotype switch)
• expresses CD27

Question 6

stem > pro-b > pre-b > immature > mature > memory or plasma

Describe what happens during the memory b cell stage. Which CD markers and Ig are expressed?

Answer 6

• isotype switching to IgG, IgA, or IgE
• expresses CD19, CD20, CD27

Question 7

What are the Ig H and L chains?

Answer 7

antigen-binding components

Question 8

What is Ig alpha/beta?

Answer 8

• aka CD79a/CD79b
• signal transduction molecules associated with Ig H chain

Question 9

Name the b-cell co-receptors (4). What is their function?

Answer 9

• CD19, CD21, CD81, CD225
• enhances signal transduction through BCR

Question 10

Name the co-stimulator molecules (4) and describe their functions.

Answer 10

• CD40: interacts with CD40L (CD154) to induce class switch recombination
• B7 (CD80, CD86): interacts with CD28 and CTLA-4 (CD152)
• ICOS ligand: interacts with ICOS on activated T cells
• cytokine receptors: receptors for T-cell derived cytokines, such as IL-4 and IFN-epsilon

Question 11

Name the homing to lymph nodes and specific tissues (3)?

Answer 11

integrins, selectins, chemokine receptors