Podcast
Questions and Answers
Which component on T cells is responsible for signal transduction?
Which component on T cells is responsible for signal transduction?
What role does CD28 play in T cell activation?
What role does CD28 play in T cell activation?
What cytokine is primarily responsible for Th1 differentiation?
What cytokine is primarily responsible for Th1 differentiation?
What outcome occurs when T cells receive only signal 1 and lack signal 2?
What outcome occurs when T cells receive only signal 1 and lack signal 2?
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Which component on APCs is involved in presenting antigens to T cells?
Which component on APCs is involved in presenting antigens to T cells?
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How do activated T cells respond to IL-2?
How do activated T cells respond to IL-2?
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What is the significance of co-stimulatory signals in T cell activation?
What is the significance of co-stimulatory signals in T cell activation?
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What type of receptor do naïve T cells express before activation?
What type of receptor do naïve T cells express before activation?
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What is the primary function of CD4+ T lymphocytes?
What is the primary function of CD4+ T lymphocytes?
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Which phase follows the activation of T lymphocytes during cellular immune response?
Which phase follows the activation of T lymphocytes during cellular immune response?
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What is NOT a type of naive CD4+ T lymphocyte?
What is NOT a type of naive CD4+ T lymphocyte?
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What signals are essential for the activation of CD4+ T lymphocytes?
What signals are essential for the activation of CD4+ T lymphocytes?
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Which statement correctly describes the role of CD8+ T lymphocytes?
Which statement correctly describes the role of CD8+ T lymphocytes?
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Which stage of the cellular immune response results in the proliferation of antigen-specific T cells?
Which stage of the cellular immune response results in the proliferation of antigen-specific T cells?
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Where does antigen recognition by naïve T lymphocytes primarily occur?
Where does antigen recognition by naïve T lymphocytes primarily occur?
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Which of the following is a feature of memory T lymphocytes?
Which of the following is a feature of memory T lymphocytes?
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Study Notes
Cellular Immune Response I
- The lecture is about Cellular Immune Response I, specifically T lymphocytes responses.
- The writer is Ali Aljaziri and the reviewer is Faisal Aloraifi.
- The lecture covers the main phases of T lymphocyte responses.
- Antigen recognition by T lymphocytes, and the role of CD4, CD8, and adhesion molecules were discussed.
- Activation signals and co-stimulation molecules for CD4+ T lymphocytes were also detailed.
- The activation process of CD8+ T lymphocytes was explained.
- The functional responses and relevance of activated T lymphocytes were explored.
- Characteristics of memory T lymphocytes and the endpoint of the cellular immune response were covered.
- The migration of effector T lymphocytes to the infection site was discussed.
- The lecture covers various types of intracellular microbes combated by T cell-mediated immunity.
- T lymphocytes play a major role in cell-mediated immunity (CMI).
- CMI defends against infections by intracellular microbes through two types of infections.
- Firstly, phagocytes ingest microbes as part of the innate immune response.
- Some microbes resist phagocytosis.
- Pathogenic intracellular bacteria and protozoa survive and replicate within phagocytic vesicles.
- Viruses infect and replicate within the cytoplasm of cells.
- Examples of intracellular microbes were given (Mycobacteria, Listeria, Legionella, Cryptococcus, Leishmania, Trypanosoma, Plasmodium, Cryptosporidium, all Rickettsiae, and all viruses).
Lecture Outline
- The lecture outlined several topics including main phases of T lymphocytes responses
- Antigen recognition and role of CD4, CD8, and adhesion molecules.
- Activation signals and co-stimulation molecules for CD4+ T lymphocytes.
- Activation process of CD8+ T lymphocytes.
- Functional responses and relevance of activated T lymphocytes.
- Memory T lymphocytes and the endpoint of the cellular immune response.
- Migration of effector T lymphocytes to the infection site.
Importance
- The doctor emphasized that every objective is a question and the student should know the answer.
- The information contained was crucial for T-cell activation and function.
T-cell Activation
- T cells recognize antigens with TCR, CD3, and zeta protein.
- APC surface molecules (MHC I or II) are important for T-cell recognition.
- Important surface molecules from T-cells and corresponding ligands were explained.
- CD28 is a co-stimulatory receptor;
- CTLA-4 and PD-1 are inhibitory receptors on T cells.
- Co-receptors (CD4 or CD8) help stabilize interactions (signal 1) with MHC-associated peptide antigens.
Costimulation
- Costimulatory signals (signal 2) between cells is essential to prevent false alarms.
- T-cell activation requires a reciprocal and sequential signal 2 exchange between cells.
- A T-cell-APC interaction begins with TCR interaction with peptide/MHC complex.
- Signals, including cytokines, control T-cell differentiation (signal 3).
- The absence of co-stimulatory molecules causes T-cell anergy or apoptosis.
CD8 T-cell Activation
- CD8+ T cells are activated by APCs (dendritic cells).
- Infected tissue cells can also activate CD8+ T cells or function as a presentation site.
- Helper T cells play a crucial role in activating CD8 T-cells
- Cytokines from helper T cells promote CD8+ T cell differentiation/expansion.
Activation Pathways
- The biochemical pathway that connects antigen recognition with T-cell responses involves enzyme activation, adaptor protein recruitment, and transcription factor production.
- These pathways are initiated when the TCR interacts with MHC on APCs.
Memory T lymphocytes
- Memory T cells persist long after an infection is cleared.
- They are important for rapid immune responses upon re-exposure.
- Central memory cells reside in lymphoid organs and promote rapid expansion while effector memory cells are present at infection sites.
Effector T Cell Migration
- Naive T cells migrate through the bloodstream and lymphoid tissues.
- Effector T cells migrate to infection sites (specific to antigen).
- Adhesion molecules (L-selectin, Integrin) and chemokine receptors (CCR7) help with migration.
- T cell migration to the infection site is independent of antigen recognition.
Functional Responses
- Cytokine production
- Clonal expansion
- Differentiation into effector cells
- Differentiation of naïve CD4 T cells into effector cells (Tfh, Th1, Th2, Th17).
- Memory T cells also help with elimination of microbes via other mechanisms in addition to effector cells.
End Point of Cellular Immune Response
- The immune system returns to homeostasis.
- Excess T cells are eliminated through apoptosis.
- Only memory cells remain for quick response to future infections.
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Description
This quiz explores the role of T lymphocytes in the cellular immune response. It covers key topics such as antigen recognition, activation, and the functional responses of CD4 and CD8 T cells. Understand the importance of memory T lymphocytes and their migration to infection sites in combating intracellular microbes.
