复旦大学：《医学免疫学 Medical Immunology》课程教学资源（PPT课件讲稿，英文版）B cell and B cell-mediated humoral immune response（2/2）

Antigen-independent development of B cells o Bcell subsets and development Fetus liver: B1 B Bone marrow: HsC→proB→preB→imB→mB spleen: NFB FP FOB○ MZB⊙

B cell subsets and development Fetus liver：B1 B Bone Marrow： HSC proB preB imB mB spleen：NF B FP FO B MZ B Antigen-independent development of B cells

three major naive peripheral B-cell populations B cell MARGINAL ZONE FOLLICULAR B1 B CELLS B CELLS B CELLS IgM IgM CD21 IgM IgD CD21 CD23 Mac- CD5 CD1 T-independent responses T-dependent responses T-independent responses ?T-dependent responses T-independent responses Mucosal Immunity Immunity to blood borne Immune responses in mos B1a cells primarily of pathogens secondary lymphoid organs fetal liver origin Self-renewing? High-affinity IgG Self-renewing Immunol rev 2004: 197: 206

three major naive peripheral B-cell populations B cell Immunol Rev 2004; 197:206 High-affinity IgG

详 INSTITUTE FOR IMMUNOBIOLOGY B cell and B cell-mediated humoral immune response Part l Department of Immunology Fudan University Wei xu ph D 021-54237749 wx2362@hotmail.com

INSTITUTE FOR IMMUNOBIOLOGY B cell and B cell-mediated humoral immune response Part II Department of Immunology Fudan University Wei Xu, Ph.D 021-54237749 wx2362@hotmail.com

Overview of the humoral immune response against bacterial Humoral response CD4+Th Antigen B cell B cells interact with antigen Ab-secreti ng Antibody binds antigen and differentiate into plasma cells and facilitates its clearance antibody-secreting plasma cells from the body B cells plasma cells

Overview of the humoral immune response against bacterial B cells plasma cells

Significance of humoral immunity eliminate extracellular bacterium and toxin eliminate extracellular virus

Significance of humoral immunity eliminate extracellular bacterium and toxin eliminate extracellular virus

B cells and humoral immune response 1. Recognition of the specific Ag 2. Activation proliferation, differentiation 2. Germinal center: laterevent 3. General feature of Ab response

B cells and humoral immune response 1. Recognition of the specific Ag 2. Activation, proliferation, differentiation 2. Germinal center: later event 3. General feature of Ab response

thymus-dependent (TD)antigens B response to TD Ag requires direct contact with Th cells thymus-independent (TI)antigens TI-1 Ag bacterial cell-wall components ipopolysaccharide (lps) TI-2 Ag highly repetitious molecules bacterial flagellin bacterial cell-wall polysaccharides with repeating units

highly repetitious molecules, bacterial flagellin bacterial cell-wall polysaccharides with repeating units. thymus-dependent (TD) antigens B response to TD Ag requires direct contact with Th cells, thymus-independent (TI) antigens TI- 1 Ag TI-2 Ag bacterial cell-wall components, lipopolysaccharide (LPS)

Recognition of TD Ag Thymus-dependent antigen ◇ Directly recognize Ag (B cell epitope) No MHC involvement B cell antigen surfaced displayed B cell-epitopes epitope antibody bcr

Recognition of TD Ag Directly recognize Ag (B cell epitope) No MHC involvement surfaced displayed B cell-epitopes

Antibodies bind to epitopes displayed on the o surface Ab(BCR)binds the B-cell epitope directly, of antigens TCR binds with a self-MHC-T-cell-epitope complex The epitopes recognized The antigen must first The epitope peptide binds The T-cell receptor binds to by T-cell receptors are be broken down into to a self molecule, an a complex of MHC molecule often buried peptide fragments MHC molecule and epitope peptide TCR epitope peptide molecule MHC molecule

Ab (BCR) binds the B-cell epitope directly, TCR binds with a self-MHC-T-cell-epitope complex

BCR-Iga/gB -coreceptor complex B cell epitope (cD21cD19-cD81) coreceptor C3d B cell epitope BCR Ag-C3d CR2 BCR CR2 Iga Igβ CD19 ga/b CD81 CD19 Signal ITAM ignal 3P13K B cell activation ++十

B cell activation B cell epitope BCR-Iga/Igb -coreceptor complex B cell epitope BCR Iga/b Signal + Ag-C3d CR2 CD19 Signal + +++ （CD21-CD19-CD81） coreceptor