2. Section 17 B cell recognition and response of antigens
B cell response to T cell-dependent antigen
B cell response to T cell-independent-antigen
Rules of antibody production
Mucosal immune response

3. B CD5+
B CD5-

4. B cell surface marker BCR FcR CR MHC-II CKR CD40 MR
（Mitogens recepter）
CD28
IL-5
IgM
B7-2
FcμR
C3b,C4b
IL-2
CD40
CD23
CD40-L
CD32
IgE
IgG
CD21
antigen
IL-4
C3bi

5. Phytohemagglutinin
PHA
Lipopolysaccharide
LPS
Pokeweed mitogen
PWM

6. TI or TD antigen CD40/CD40L B1 cell B2 cell Th cell TI-1 antigen

7. TI-Ag induced humoral responses
TD-Ag induced humoral responese
Effect of humoral immune responese
Features of primary and secondary response
Regulation of humoral immune response
Theories of antibody formation

8. TI-1 and TI-2 antigens LPS B cell TI-1 antigen LPS recepter
Signal transduction
B cell
Signal transduction

9. Features of response to TI-Ag
No requirement of involvement of Th cell
No memory B cell are formed
IgM is the predominant，no class switch and no affinty matuation

10. The humoral immune response to TI antigens
Antibody concentration in serum,（Log）
primary
secondary
100000
10000
1000
100 10 1
IgM
days

11. The humoral immune response to TD antigens
Th cell activation
Th1 Bm B7
CD28 Th
CD4
Plasmacyte
MHC-II TCR B
ICAM LFA-1
APC
secreting cytokins B B
Th2
CD40L CD40 B
BCR
antigen
B cell expansion

15. antibody class switching and
affinity maturation
Plasmacyte
IgG2a or
IgG3 g
Activited B cell
IFN-
IgA or
IgG 2b
TGF- β
IL-2
IL-4
IgE
IL-5
IL-4
IL-2
IgM
IL-4
IL-5

16. Somatic hypermutation of Ig genes roles in Ab Affinity maturation)

17. Affinity of Ag-Ab binding

18. Avidity of Ag-Ab binding

19. Non-covalent bonds essential for Ag-Ab binding
antibody O H = –
ionic bond
–C –O – H –N – –
Van der Waals forces H
antigen
hydrogen bond
–C=O……………H –N –
hydrophobic bond
H2O

20. Effect of humoral immune response
Pathway :
Neutralizing toxin & virus
fixation of complement
opsonization
mediating ADCC
Effect ：
preventing infections（extracellular）
—anti-bacterial , anti-viral anti-toxic
mediating hypersensitivity I II,III
mediating autoimmunity

21. 1 2 3 4 5 6

22. Primary and Secondary Humoral Response
Antibody concentration in serum,（Log）
First immunization
Second immunization
100000
10000
1000
100 10 1
primary
secondary
IgG
IgM
days

23. The humoral immune response to TI antigens
Antibody concentration in serum,（Log）
primary
secondary
100000
10000
1000
100 10 1
IgM
days

24. Features of primary and secondary response
primary response
secondary response
Responding B cell
naive B cell Bm Ag
TI-Ag or TD-Ag
TD-Ag
Lag period
4-7days
1-3days
lower
higher
Peak concentration of antibody
Isotype produced
IgM
IgG、IgA etc
Antibody affinity
lower
higher

25. Regulation of humoral immune response

28. Antiboy-mediated suppression
antigen
IgG
BCR
FcgRII
suppression
Igα
Igβ
phosphorylase
B cell

29. Theories of Ab Formation
Side chain theory
Template theory
Clonal selection theory

30. Side chain theory

31. Template theory Ab Ag

32. Clonal selection theory
Frank Burnet
Nobel Prize 1960

33. antigen-A
Lag period
：T / B cell clonal to antigen A

34. The Clonal Selection Theory1 2
The Clonal Selection Theory 3 n

35. Lymphocytes 1 2 3 n
Antigen

36. ? Lymphocytes Plasma cells 1 3 3 3 2 3 3 3 3 3 3 3 n 3
(? How large is “n”?)
Plasma cells 1 3 3 3 2 3 3 3 3 3 3 3 n 3

38. 1. Master the humoral immune response （the features of response to TI-Ag ,the features of Interaction of the cells during the response ）
2. Master the principle of antibody formation（Comparison of primary and secondary response ）

39. Thanks !