B Cells: Development, Activation and Function

1
B Cells Development, Activation and Function

• January 25, 2001

2
B Cells The Immune Systems Shaq Attack
3
Outline

• B Cell Development and Maturation
• B Cell Activation, Proliferation
• Primary and Secondary B Cell Responses
• B Cell Differentiation

4

• 3 Stages of the B Cell
• Generation (antigen independent)
• Activation (antigen dependent)
• Differentiation (antigen dependent)

5
Fig. 11-2
6
Fig. 11-4
7
5-6 cell divisions
Fig. 11-3
8
(No Transcript)
9
http//www.bio.davidson.edu/Biology/Courses/Immuno
logy/Flash/Bcellmat.html
10
Clonal Deletion
X
11
http//www.bio.davidson.edu/Biology/Courses/Immuno
logy/Flash/Bselect.html
12
Outline

• B Cell Development and Maturation
• B Cell Activation, Proliferation
• Primary and Secondary B Cell Responses
• B Cell Differentiation

13
Thymus-Dependent and Thymus-Independent Antigens

• T-dependent response requires physical contact
  between T cell and B cell
• T-independent response do not require T cell
  contact
• Can be divided into TI-1 responses and TI-2
  responses
• TI-1 (e.g. LPS) are polyclonal B cell activators
  (mitogens)
• TI-2 (e.g. polysaccharides) crosslink mIg
  non-mitogenic, require cytokines
• TI response is weaker, no memory cells are
  formed, and IgM is primary antibody secreted

14
Cell Signaling/Signal Transduction
15
http//www.bio.davidson.edu/Biology/Courses/Immuno
logy/Flash/TI.html
16
Fig. 11-6
17
Fig. 11-10
18
Outline

• B Cell Development and Maturation
• B Cell Activation, Proliferation
• Primary and Secondary B Cell Responses
• B Cell Differentiation

19
(No Transcript)
20
Table 11-4
21
Hapten/Carrier Response
22
Outline

• B Cell Development and Maturation
• B Cell Activation, Proliferation
• Primary and Secondary B Cell Responses
• B Cell Differentiation

23
Differentiation in Germinal Centers (GCs)

• Germinal centers are sites in secondary lymphoid
  tissues where massive B cell proliferation occurs
  in response to T-dependent antigen stimulation
• GCs are the sites of
• Isotype switching change in antibody isotype
  without loss of specificity
• Affinity Maturation - increase in antibody
  affinity due to selection of high-affinity B cell
  clones which arise as a result of somatic
  V-region hypermutation
• Differentiation into plasma or memory cells

24
(No Transcript)
25
Clonal Selection
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Antibody-Producing Plasma Cells
Y
Memory Cells
Y
Y
Y
Y
Y
Y
Y
26
B1 B Cells

• A small subset of human and mouse B cells, but
  they arise earlier. Consequently, most typical
  B cells are referred to as B2 B cells
• Found primarily in the peritoneal cavity. Scarce
  in the LN, spleen.
• Respond poorly to protein antigens, better to
  carbohydrate antigens
• Many chronic lymphocytic leukemias arise from B1
  cells
• Role in autoimmune diseases has been speculated

27
(No Transcript)