Immature B cells develop into mature B cells in secondar

1
B Cell Development

• Kathleen E. Sullivan MD PhD
• Childrens Hospital of Philadelphia

2
Pro-B Pre-B1 Pre-B2 Immature B Mature B
Plasma
MHC II
CD19
CD22
CD34
Iga/b
VpreB, l5
CD10
CD20
VDJ
V-J light
D-J
3
Immature and Mature B cells

• Pre B cells must undergo positive selection of
  correct heavy chains expressed with VpreB and l5
• Immature B cells exposed to antigen usually die
  (deletion of autoreactive B cells)
• Immature B cells develop into mature B cells in
  secondary lymphoid organs
• Mature B cells exposed to antigen become activated

4
A few other ways to prevent autoreactivity

• Immature autoractive B cells can undergo receptor
  editing- try again
• Anergy Seen with autoreactivity that is low
  affinity. Anergic B cells are excluded from the
  lymph node follicles and have a short life span
• Ignorance Seen with weakly reactive B cells

5
Germinal center development
Follicular B cell
Primary blast
Centroblast
Centrocyte
Dark zone
Light zone
Dark zone
CD40CD40L
Somatic HM
6
A few B cell markers used in flow cytometry
Total B cells CD19 Total B cells CD20 Naive
B cells CD19, IgD, CD10 (report triple
) Naive B cells CD19, IgD, IgM (report
triple ) Mature B cells CD19, CD20-, IgG
(report as shown) Memory B cells CD19, CD27,
IgM (report triple ) Switched memory CD19,
CD27, IgM- ( as shown) B1 B cells CD19, CD5
(report double ) HIGMII CD19, CD40 (report
double )