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What is the name given to T-cells undergoing maturation in the thymus?
What is the name given to T-cells undergoing maturation in the thymus?
Thymocytes
What are the two types of CD proteins?
What are the two types of CD proteins?
MHC I are found on the cell surface of all nucleated cells.
MHC I are found on the cell surface of all nucleated cells.
True
Which of the following cell types are specialized antigen presenting cells (APCs)? (Select all that apply)
Which of the following cell types are specialized antigen presenting cells (APCs)? (Select all that apply)
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What is the term for the process where T-cells that bind to self-antigens with high affinity are eliminated?
What is the term for the process where T-cells that bind to self-antigens with high affinity are eliminated?
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CD4 binds to MHC I and CD8 binds to MHC II.
CD4 binds to MHC I and CD8 binds to MHC II.
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What is the rule of 8?
What is the rule of 8?
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What is the name given to the membrane-bound glycoprotein similar to the Fab fragment found on T cells?
What is the name given to the membrane-bound glycoprotein similar to the Fab fragment found on T cells?
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What are the three regions of the TCR?
What are the three regions of the TCR?
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TCR recognizes antigens presented on host cells.
TCR recognizes antigens presented on host cells.
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What are the main outcomes of T-cell activation?
What are the main outcomes of T-cell activation?
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What are the two major subtypes of T cells?
What are the two major subtypes of T cells?
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Which subtype of T cell is involved in recognizing antigens on MHC II?
Which subtype of T cell is involved in recognizing antigens on MHC II?
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TH2 cells secrete IL-2 and IFN-gamma.
TH2 cells secrete IL-2 and IFN-gamma.
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What is the role of TH1 cells?
What is the role of TH1 cells?
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Treg cells activate TH17 cells.
Treg cells activate TH17 cells.
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What is the process where dendritic cells present antigens from a pathogen on both MHC I and MHC II?
What is the process where dendritic cells present antigens from a pathogen on both MHC I and MHC II?
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Which of the following is NOT a mechanism of T cell activation?
Which of the following is NOT a mechanism of T cell activation?
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The activation of a T cell leads to the expression of IL receptors by the activated cell. This is known as autocrine activation.
The activation of a T cell leads to the expression of IL receptors by the activated cell. This is known as autocrine activation.
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What is the role of the effector cells?
What is the role of the effector cells?
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Effector cells can give rise to long-lived memory cells.
Effector cells can give rise to long-lived memory cells.
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What are the two main mechanisms of CD8 cell activation?
What are the two main mechanisms of CD8 cell activation?
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CD8 T cells are cytotoxic cells that destroy virus-infected cells.
CD8 T cells are cytotoxic cells that destroy virus-infected cells.
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What are the two main arms of the adaptive immune response?
What are the two main arms of the adaptive immune response?
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Where is the humoral immune response initiated?
Where is the humoral immune response initiated?
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The humoral immune response can protect against intracellular pathogens.
The humoral immune response can protect against intracellular pathogens.
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Connect the different phases of an adaptive immune response with their key features:
Connect the different phases of an adaptive immune response with their key features:
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Study Notes
Adaptive Immune System - Part 2
- The adaptive immune system is activated when the innate immune system is overwhelmed.
- It involves two main branches: T cell-mediated and antibody-mediated (humoral).
- T cell activation requires antigen presentation.
- B cell activation occurs without the need for antigen presentation.
T-Cell Maturation and Activation Mechanisms
- T cells originate in the bone marrow.
- Immature T cells (thymocytes) migrate to the thymus for maturation.
- T-cell maturation involves:
- Rearrangement of the T-cell receptor (TCR).
- Positive selection: Thymocytes binding to MHC I or II molecules survive.
- Negative selection: Thymocytes binding strongly to self-peptides or MHC complexes undergo apoptosis.
- Mature T cells then migrate to lymph nodes.
T-Cell Functions
- CD8 T cells (Tc) recognize antigens on MHC class I molecules and kill infected cells via apoptosis.
- CD4 T cells (Th) recognize antigens on MHC class II molecules.
- Th1 cells activate macrophages and produce IFN-γ
- Th2 cells activate eosinophils and mast cells, & support B cell antibody production.
CD4 T Cell Subsets and Functions
- Th1 cells produce IFN-γ, which activates macrophages, cytotoxic T cells, and other cells
- Th2 cells support antibody production by B cells, which is crucial for defense against pathogens that are outside of cells.
- Th17 cells produce IL-17, which promotes inflammation and neutrophil activity, which is important in defense against extracellular bacteria and fungi.
- Treg cells (regulatory T cells) suppress immune responses, which is important in preventing autoimmune diseases and limiting excessive inflammation.
Professional Antigen-Presenting Cells (APCs)
- APCs are crucial for T cell activation.
- Professional APCs, such as dendritic cells, macrophages, and B cells present antigens on their MHC class I and II molecules.
- Dendritic cells, macrophages, and B cells have different roles and characteristics.
Antigen Cross-Presentation
- Dendritic cells can cross-present antigens, meaning they can present intracellular pathogens on MHC class I and II molecules.
- This process triggers activation of both CD4+ and CD8+ T cells.
T-Cell Receptor (TCR) Structure
- The TCR is a membrane-bound glycoprotein with two polypeptide chains (alpha/beta or gamma/delta).
- TCR regions include variable (V) and constant (C) regions.
- Recognizes antigens presented on host cells (either MHC class I or MHC class II)
T-Cell Activation Mechanisms
- Specific antigen-MHC complex interaction with TCR.
- Supporting interactions from CD4 or CD8 co-receptors.
- Intracellular signaling and stabilization of the MHC-TCR connection.
- Co-stimulation from professional APCs like dendritic cells, macrophages, and B cells.
T-Cell Proliferation and Differentiation
- Activated T cells proliferate and differentiate into effector and memory T cells.
- Effector cells have short-lived and carry out immune functions directly
- Memory cells are long-lived, which provide protection against future infections.
Lymphocyte Activation and Differentiation (Summary)
- T-cell precursors undergo positive selection (cortex) and negative selection (medulla) in the thymus to become mature T cells.
- T-cell activation in lymph nodes involves antigen recognition and co-stimulation by professional APCs.
- Activated T cells differentiate into distinct effector (e.g., Th1, Th2) and memory subsets.
Summary of Adaptive Immune Response Phases:
- Antigen recognition by lymphocytes
- Lymphocyte activation
- Antigen elimination by effector cells
- Contraction (homeostasis) and memory development
Task 1: Immune System Parts (Template information)
- The document provides an example of a potential task where students need to fill an immune system template with specific criteria.
Task 2: Revision Questions
- The document suggests that revision questions will be answered at the end of the session.
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Description
Explore the workings of the adaptive immune system in this quiz focusing on T-cell maturation, activation mechanisms, and their functions. Understand how T cells respond to antigens and the critical processes involved in ensuring immune efficiency.
