浙江大学医学院：体液免疫（PPT讲稿）Humoral Immune response

Humoral Immune response Jianzhong Chen, Ph.D. Institute of Immunology, ZJU

Jianzhong Chen, Ph.D. Institute of Immunology, ZJU

B cell-mediated humoral Immune response o Humoral immunity is mediated by antibodies and is the arm of the adaptive immune response that functions to neutralize and eliminate extracellular microbes and microbial toxins eIt is more important than cellular immunity in defending against microbes with capsules rich in polysaccharides and lipids, and against polysaccharide and lipid toxins

B cell-mediated humoral immune response  Humoral immunity is mediated by antibodies and is the arm of the adaptive immune response that functions to neutralize and eliminate extracellular microbes and microbial toxins.  It is more important than cellular immunity in defending against microbes with capsules rich in polysaccharides and lipids, and against polysaccharide and lipid toxins

1. Phases and types of humoral Immune responses 1)Phases o Antigen recognition phase Activation, proliferation and differentiation phase ● Effector phase 2) Types ° Response to TD-Ag Response to TI-Ag

1. Phases and types of humoral immune responses 1) Phases  Antigen recognition phase  Activation, proliferation and differentiation phase  Effector phase 2) Types  Response to TD-Ag  Response to TI-Ag

Antigen Activation of Effector phase recognition B lymphocytes Effector cells antibody secreting Helper T cells cells other stimuli Antibody Clonal secretion Naive IgM+ IgD+ expansion o IgG IgG B cell →-的 celle Class switching Activated B cell Microbe →◎x Affinity maturation High-affinit Ig-expressing B cell High Affinity IgG Memory B cell (ElsevierAbbas&LichtmanBasicImmunologyupDated2e-www.studentconsult.com Phases of humoral immune responses

Phases of humoral immune responses Effector phase

2. Response to TD-Ag

2. Response to TD-Ag

1)Bcells recognize TD-Ag a bcr directly recognizes B cell epitopes b Iga/IgB transfer the first signal C Effect of coreceptors( CD21/CD19/CD81) d signalling pathways

1) B cells recognize TD-Ag a. BCR directly recognizes B cell epitopes b. Ig/Ig transfer the first signal c. Effect of coreceptors (CD21/CD19/CD81) d. Signalling pathways

业 epitope antigen BCR directly recognize B cell epitope

BCR directly recognize B cell epitope

Microbe Complement Bound activation C3d CR2 Recognition CD19 by b cells Iga/B CD81 Signals from Ig and CR2 complex B cell activation CElsevierAbbas&Lichtman:BasicImmunologyUpdated2e-www.studentconsult.coml The role of coreceptor(CD19/CD21/CD81)in B cell activation

The role of coreceptor (CD19/CD21/CD81) in B cell activation

Q Microbe Cross-linking Adapter of membran proteins Ig by antigen Tyrosine ITAM hosphorylation events PLCY GTP/GDP exchange activation in Ras. Rac Biochemical intermediates Inositol trisphosphate s increased cytosolic Ca2+Diacylglycerol(DAG)Ras GTP, RacGTP Active Ca2+-dependent enzymes PKC enzymes ERK,JNK Transcription factors NFAT NF-KB △p C Elsevier. Abbas& Lichtman cimMunologyUpdated2e-www.studentconsult.com BCR complex-mediated signal transduction in B cells

BCR complex-mediated signal transduction in B cells

Antigen binding tol Activation of Changes in and cross-linking B lymphocytes phenotype Functional consequences of membrane Ig function of Ig-mediated B cell activation Entry into cell cycle: mitosis Increase in expression of Naive B costimulators(such as B7) lymphocyte B7 Increased expression of costimulators 2. Increase in expression of and cytokin CKRs Cytokine receptors receptor 3. Decrease in their MIgM expression of receptors Low level IgM secretion for chemokines produced in lymphoid folicles B cell response to antigen Significance Entry into cell cycle, mitosis Clonal expansion ncreased expression o Ability to activate B7 costimulators helper T cells Increased expression of Ability to respond to cytokines cytokine receptors produced by helper T cells Migration out of Interaction with lymphoid follicles helper T cells Secretion of low levels Early phase of humoral of igM Immune response ElsevierabBas&LichtmanBasicImmunologyupdated2e-www.studentconsult.co

Functional consequences of Ig-mediated B cell activation: 1. Increase in expression of costimulators (such as B7) 2. Increase in expression of CKRs 3. Decrease in their expression of receptors for chemokines produced in lymphoid folicles