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Lecture 3: Antigen Recognition by T lymphocytes
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Questions to Consider
How do B cells and T cells see antigen?
How does a T cells distinguish between whether a foreign antigen is being presented to recruit help or because the cell is infected?
Why do some T cells kill and others provide help?
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Phagocytosis by Macrophages
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Antigen Presenting Cells
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Activation of Macrophages PermitsElimination of Mycobacterium Infection
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Changes Exhibited by an Activated Macrophage
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Development of a Secondary Amplified Response
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T-cell Activation of Macrophages
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Transfer of Which Cells Will Protect This Mouse From TB?
Activated monocytes
T cells
B cells
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T-cell Activation of Macrophages Permits Killing of Phagocytosed Pathogens
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How does the T cell know that the macrophage is infected with TB?
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B Cells and T Cells Use Different Antigen-specific Receptors
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T Cell Receptor Gene
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Genetic Rearrangement Generates T Cell Receptor Diversity
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Development of a Secondary Amplified Response
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T Cells and B Cells Recognize Antigen Differently
Secondary Immune Response
Primary Immunization
Secondary Ag Challenge B Cell Response T Cell Response
Native Protein Native Protein + + Denatured
Protein Native Protein - +
Native Protein Denatured Protein - +
Denatured Protein
Denatured Protein + +
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The T Cell Receptor Only Recognizes Antigen in the Presence of Antigen Presenting Cells
Abbas- Cellular and Molecular Immunology
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Antigen Must Be Processed to Peptides to be Recognized by the T Cell Receptor
Abbas- Cellular and Molecular Immunology
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Antibody and T Cell Receptors Recognize Different Antigenic Contexts
B Cells use the Immunoglobulin Molecule to recognize 3D structures of the native molecules.
T Cells use theT cell receptor to recognize primary structures.
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While the Majority of MHC-expressed Peptides are Self Self-reactive T Cells Are Not Present in the Periphery
Abbas- Cellular and Molecular Immunology
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Two Different Types of MHC Molecules Are Capable of Presenting Peptides to T Cells
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Divergent Cellular Expression of Class I and Class II MHC Molecules
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Peripheral T Cells Express Either CD4 or CD8 Molecules
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TCR Interaction With APCs Is Limited by CD4 or CD8 to Either MHC Class I or II, Respectively
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Functional Implication of CD4 or CD8 Restricted Recognition of Class I or Class II MHC Molecules
Abbas- Cellular and Molecular Immunology
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MHC Class I Molecules Only Present Peptides Derived From Endogenous Proteins
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Cells Expressing Foreign Peptides Recognizedby Cytotoxic CD8+ T Cells Are Killed
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Antigen Presenting Cells
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MHC Class II Molecules Present Only Peptides Derived From Exogenous Proteins
Mon
ocyt
esB
Cel
ls
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CD4+ T Cells Stimulate Cells Expressing Foreign Peptides That They Recognize
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B Cells Present Peptides Derived FromProteins Recognized by Surface Antibody
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Correlation of Pathogen Location, MHC Presentation and T Cell Effector Function
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NATURE |VOL 391 | 22 JANUARY 1998
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Natural Killer (NK) Cells Prevent Evasion of CTL Immunity by Downregulation of MHC Class I MHC Molecules
Killer inhibitory receptors- KIR interact with MHC and prevent the NK cells from killing target cells
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HIV Can Evade This Immune Response Too
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Questions to Consider
How do B cells and T cells see antigen?
How does a T cells distinguish between whether a foreign antigen is being presented to recruit help or because the cell is infected?
Why do some T cells kill and others provide help?