Download
1 / 15
150 likes | 273 Vues
This comprehensive overview discusses the intricate dynamics of the immune response, focusing on the phases of antibody development against T-dependent antigens. Key topics include the self/non-self discrimination mechanism, memory formation, specificity, and the equilibrium, catabolic decay, and immune elimination phases. It highlights the kinetic patterns in both primary and secondary antibody responses, emphasizing the qualitative changes in antibody classes and affinities. Additionally, cellular events during responses unveil the role of memory cells and cytokines in long-term immunity, addressing critical concepts such as class switching and clonal selection.
E N D
Hallmarks of the Immune Response • Self/Non-self Discrimination • Memory • Specificity
Equilibrium Phase 100 75 Catabolic Decay Phase Amount of Circulating Ag (%) 50 Immune Elimination Phase 25 8 4 2 6 10 12 Days after Injection Fate of the Immunogen • Clearance after 1o exposure • Equilibrium phase • Catabolic decay phase • Immune elimination phase • Clearance after 2o exposure • More rapid onset of immune elimination phase
LOG PLATEAU DECLINE LAG A b T i t e r Ag D a y s A f t e r I m m u n i z a t i o n Kinetics of the Ab ResponseT-dependent Ag; 1o Response • Lag phase • Log phase • Plateau phase • Decline phase
2o Ag 1o Ag A b T i t e r D a y s A f t e r I m m u n i z a t i o n Kinetics of the Ab ResponseT-dependent Ag; 2o Response • Lag phase • Log phase • Plateau phase • Decline phase * Specificity
Total Ab IgG Ab IgM Ab 2o Ag 1o Ag A b T i t e r D a y s A f t e r I m m u n i z a t i o n Qualitative Ab Changes during 1o and 2o Responses • Class variation • 1o - IgM • 2o - IgG, IgA or IgE
IgM Ab IgG Ab 2o Ag 1o Ag Low Dose A f f I n I t y High Dose D a y s A f t e r I m m u n i z a t i o n Qualitative Ab Changes during 1o and 2o Responses • Class variation • Affinity • Affinity Maturation
High Ag Concentration 1010 109 108 107 106 105 Moderate Affinity Ab Low Ag Concentration 1010 109 108 High Affinity Ab 107 106 105 Qualitative Ab Changes during 1o and 2o Responses • Class variation • Affinity • Clonal selection • Somatic mutation
Qualitative Ab Changes during 1o and 2o Responses • Class variation • Affinity • Avidity • Cross reactivity
1o Ag IgM IgG Memory Cells Cellular Events in 1o Response to T-dependent Ags • Lag • Clonal selection • Log • IgM • Class switching • Stationary • Decline • Memory Cell Pool
IgM Virgin B cell IgG Memory Cells Memory Pool IgG Memory Cells Cellular Events in 2o Response to T-dependent Ags • Lag phase • Virgin cells • Memory cells • Log phase • Pool size • IgG, IgA or IgE • Stationary • Decline • Sustained production
Virgin cell Th Th Memory Cells Memory Pool Th Memory Cells Memory T cells • T Cells • Virgin cells • Memory cells • Th cells • Cytokines • Long Term Memory
IgM Ab 2o Ag 1o Ag A b T i t e r D a y s A f t e r I m m u n i z a t i o n Kinetics of Ab Response toT-independent Ags • 4 Phases • IgM antibody • No secondary response
Class Switching DNA rearrangement Antigen dependent Switch site Same VDJ TH cytokines
Polyadenylation Sites H3 H4 M M DNA H3 H4 H3 H4 M M Primary Transcript AAAA AAAA H3 H4 M M H4 H3 AAAA AAAA mRNA Secreted Membrane Bound Membrane vs Secreted Ig • Differential pre-mRNA processing • Membrane exons • Alternate polyA sites • Same VDJ region used
