Questions and Answers
Which of the following cytokines is NOT produced by Th17 cells?
Which of the following is NOT a function of Treg cells?
Which type of T cell primarily helps B cells to produce antibodies?
Which of the following is NOT a cytokine produced by Th1 cells?
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Which type of T cell primarily helps CD8+ T cells become cytotoxic?
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Which of the following cytokines is NOT directly involved in the differentiation of naïve CD4+ T cells into effector T cell subtypes?
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Which type of effector T cell primarily contributes to the suppression of immune responses?
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Which of the following is NOT a mechanism by which Treg cells suppress immune responses?
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Which molecules are involved in presenting peptides to T cells?
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What is the total number of signals required for T cell activation?
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What type of T cells are classified as cytotoxic lymphocytes?
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Which of the following correctly represents the structure of MHC class I?
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What do CD4+ T cells primarily recognize?
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Which term best describes the genes encoding MHC class I and II molecules?
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What is the function of co-stimulatory molecules during T cell activation?
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Which subtype of T cell is primarily involved in helping B cells and CD8+ T cells?
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What type of signal is recognized by the T cell receptor (TCR)?
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Which cells express MHC class II molecules?
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Study Notes
T Cell Antigen Recognition
- Peptides are displayed by cells in the context of highly polymorphic MHC molecules
- T cells recognize peptides with their T cell receptors
MHC Molecules
- MHC I:
- Associates with β2 microglobulin
- Expressed on all nucleated cells
- Displays peptides from endogenously expressed proteins
- MHC II:
- Expressed on specialized antigen-presenting cells (APCs): monocytes, macrophages, dendritic cells, and B lymphocytes
- Displays peptides from exogenously derived proteins
Sources of Peptides Loaded into MHC Class I and II
- MHC class I: viruses and other intracellular pathogens
- MHC class II: extracellular pathogens and proteins
Structure and Function of MHC Molecules
- Highly polymorphic genes encoding MHC class I and II
- MHC molecules are heterodimers (α and β chains) for MHC I and II
T Cell Receptors (TCRs)
- T cells are defined by expression of the T cell receptor
- TCRs are membrane-bound heterodimers (α and β chains) with variable and constant domains
- TCR genes undergo rearrangements from germline before translation
- Two subtypes: αβ and γδ
T Cell Activation
- Activation of T cells requires two signals: Signal 1 (TCR-MHC interaction) and Signal 2 (co-stimulation)
- Co-stimulatory molecules (CD28 and CD86) are upregulated on APCs by 'danger signals' (infection and inflammation)
CD8 T Cells
- Recognize peptides presented by MHC I
- Cytotoxic T cells that can kill target cells (virally infected or cancerous cells)
CD4 T Cells
- Recognize peptides presented by MHC II
- Can differentiate into different kinds of effector T cells with distinct functions:
- Th1: produce IFN-γ and help activate CD8 T cells and macrophages
- Th2: produce IL-4 and help activate B cells
- Th17: produce IL-17 and help fight extracellular pathogens
- Treg: suppress immune responses and maintain self-tolerance
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Description
A comprehensive quiz covering lectures 2-5 of immunology, including innate immune response, antibody diversity, lymphocytes, T cells, MHC, and tolerance.
