Download presentation
Presentation is loading. Please wait.
Published byCalvin Grant Modified over 8 years ago
1
11. B Cell Recognition and Response to Antigens 王 家 鑫王 家 鑫
3
TDAgTIAg
4
Stages of Humoral Immune Response
5
11-1 B Cell Response to T Cell-Dependent Antigen (TD)
8
Colocalization of T cells and B cells at the follicular border 2 days into the primary response.
9
Nature Reviews Immunology 3, 962-972 (2003)
10
1. B Cell Receptor Complex
12
2. Activation of B cells
14
Two-Signal Model of Humoral Immune Response
18
Signals generated from the B-cell receptor and co-receptor synergize in B-cell activation. Binding of CR2 to C3d deposited on the surface of a pathogen cross-links the B-cell co-receptor complex with the B-cell receptor.
19
Model of the role for lipid rafts in B-cell activation
20
B Cell Receptor Complex
22
Activation of B Cells in Spleen
24
Response Events in Germinal Center — Affinity Maturation and the Generation of Memory B Cells
26
Immune complexes bound to follicular dendritic cells form iccosomes, which are released and can be taken up by B cells in the germinal center
27
Somatic hypermutation
28
Nature Reviews Immunology 2, 688-698 (2002)
29
Class Switching DNA rearrangement –Antigen dependent –Switch site –Same VDJ –T H cytokines During B cell development, many B cells switch from making one class of antibody to making another, this process is called class switching.
30
Antibody Class Switching
31
Class switching in immunoglobulin heavy chain genes
33
Class Switching Recombination Class-switch recombination (CSR) of immunoglobulin heavy chains is the genetic process by which a B cell switches from the production of IgM to the production of IgG, IgE or IgA.
34
Cellular interactions important for IgE class-switch recombination
38
Affinity = attractive and repulsive forces Ab Ag High Affinity Ab Ag Low Affinity Affinity Strength of the reaction between a single antigenic determinant and a single Ab combining site
39
Avidity The overall strength of binding between an Ag with many determinants and multivalent Abs K eq = 10 4 Affinity 10 6 Avidity 10
40
Ag1 Ab1 Ag1 Ab1 Affinity and avidity 亲和力与亲合力
41
IgA+ plasma cells in green, IgG+ plasma cells in red. Lymph node
42
λlight chain in yellow,κlight chain in red. Bone marrow
43
Bone marrow is the home of plasma cells
44
Summary Antigen-Induced Migration of B Cells and Helper T Cells Helper T Cell-Mediated Activation of B Cells: The Role of CD40-CD40L Interactions and Cytokines B Cell Differentiation into Antibody-Secreting Cells Heavy Chain Isotype (Class) Switching
45
2. Basic Features of Humoral Immune Response B Cell Subsets CD5+ B Cells→B1 Cells, TI Ag CD5- B Cells →B2 Cells, TD Ag CD9+ B Cells, TI Ag. No memory B Cells Response to T Cell-Dependent Antigens (TD Ag) Primary Humoral Immune Response Second Humoral Immune Response
46
B Cells Response to T Cell-Independent Antigens (TI Ag). LPS, Glycolipid, Nucleic acid. ★ No memory and no MHC restriction. CD9+B cell Response in Early Stage of Foot-and-Mouth Disease Virus Infection.
47
CD5+ CD9+ CD5-
49
11-2 B Cell Response to T Cell-Independent Antigens (TI)
53
Thymus- independent (TI)-1 antigens can activate B cells without T-cell help No Memory, no class switching
55
11-3 Effector Mechanisms of Humoral Immune Response
57
Neutralization
58
Opsonization Macrophage Extracellular bacteria Opsonization Ingestion by macrophage Digestion in lysosome
60
Complement Activation C2 C4 C1 Digestion in lysosome Bacteria in plasma C1 C4 C2 Complement activation Lysis and ingestion
63
Thank You! From farm animals to “pharm” animals
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.