Podcast
Questions and Answers
What role do lymph node macrophages play in the immune response?
What role do lymph node macrophages play in the immune response?
What is the initial fate of B-cells when they recognize an antigen in the lymph node?
What is the initial fate of B-cells when they recognize an antigen in the lymph node?
What occurs within 48 hours after a B-cell binds with an antigen?
What occurs within 48 hours after a B-cell binds with an antigen?
Which of the following statements concerning T-cell activation is true?
Which of the following statements concerning T-cell activation is true?
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What is the primary function of the IgD antibody in B-cell activation?
What is the primary function of the IgD antibody in B-cell activation?
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What is the primary role of cytotoxic T cells (CD8/Tc cells)?
What is the primary role of cytotoxic T cells (CD8/Tc cells)?
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Which molecule is essential for T-cells to recognize antigens?
Which molecule is essential for T-cells to recognize antigens?
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What happens during the clonal expansion of T cells upon activation?
What happens during the clonal expansion of T cells upon activation?
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Which type of T cell is primarily responsible for activating B-cells?
Which type of T cell is primarily responsible for activating B-cells?
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What is the major consequence of HIV targeting CD4 T cells?
What is the major consequence of HIV targeting CD4 T cells?
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How are microbial antigens presented on MHC class II molecules?
How are microbial antigens presented on MHC class II molecules?
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Which cytokines do helper T cells primarily release to assist in immune activation?
Which cytokines do helper T cells primarily release to assist in immune activation?
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What is a key feature of the T-cell receptor (TCR)?
What is a key feature of the T-cell receptor (TCR)?
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Flashcards
T cells and B cells activation
T cells and B cells activation
Immune cells that recognize antigens and become activated in lymph nodes.
B-cell activation process
B-cell activation process
B-cells stay in lymph nodes, process antigens, and bind with IgD to prepare for activation.
Clonal selection of T-cells
Clonal selection of T-cells
T-cells proliferate into cytotoxic (Tc) and helper (Th) cells after detecting an antigen.
Plasma cell production by B-cells
Plasma cell production by B-cells
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Classes of antibodies produced
Classes of antibodies produced
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T-cells
T-cells
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Cytotoxic T cells
Cytotoxic T cells
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Helper T cells
Helper T cells
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MHC I
MHC I
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MHC II
MHC II
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Clonal expansion
Clonal expansion
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Activation of B cells
Activation of B cells
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Antigen presentation
Antigen presentation
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Study Notes
T-Cell Activation
- T-cells mature in the thymus.
- Each T-cell has a unique T-cell receptor (TCR) that recognizes specific antigens.
- T-cells recognize antigens presented on the surface of infected cells.
- Effective against viruses and intracellular pathogens.
- Types:
- Cytotoxic T cells (CD8/Tc cells): Kill cancerous or infected cells.
- Helper T cells (CD4/Th cells): Activate the immune system via cytokines.
- T-cells recognize infected cells via antigens presented on MHC molecules (major histocompatibility complex).
- MHC Class I (MHC I): Found on all nucleated cells in the body. Presents foreign proteins.
- Foreign proteins digested by proteasomes.
- Foreign peptides delivered to MHC I via the endoplasmic reticulum (ER).
- Recognized by cytotoxic T cells (Tc cells), leading to cell death.
- Mechanism:
- Infected cell presents antigen on MHC I.
- Tc cell recognizes the antigen via its TCR.
- Tc cell kills the infected cell using granzymes and perforin.
- MHC Class II (MHC II): Found on dendritic cells and macrophages. Involved in surveillance and triggering immune responses.
- Microbes digested within phagosomes.
- Microbial peptides loaded onto MHC II and presented on the cell surface.
- Recognized by helper T cells (Th cells), which secrete cytokines to activate antigen-presenting cells (APCs).
- Mechanism:
- Dendritic cells (DCs) present antigen on MHC II in lymph nodes.
- Th cells are activated.
- Th cells release cytokines to activate immune cells.
Antigen Presentation (Summary)
- Infection occurs.
- DCs present antigens to T-cells in lymph nodes.
- T-cells are activated and released.
- Tc cells kill infected cells.
- Th cells activate DCs/macrophages presenting the antigen.
- Memory T-cells are produced.
Clonal Expansion of T-cells
- Activated by dendritic cell proliferation (1-2 days).
- Effector cells (Th CD4 and Tc CD8) leave lymphoid tissue.
- Importance of Th cells:
- Allow B-cells to become plasma and memory cells.
- Stimulate Tc cells to proliferate and kill infected cells (e.g., IFN-γ and TNF-α).
- Activate macrophages to kill pathogens.
- HIV targets CD4 cells: Compromises the immune system.
B-Cell and T-Cell Activation
- Naive T-cells and B-cells migrate to lymph nodes/spleen after maturation.
- Continue circulating in the body.
- Upon infection:
- Microbes enter.
- Antigens presented in lymph nodes (by DCs).
- Free antigens enter the blood (spleen).
- T-cells and B-cells recognize and become activated.
Antigen Entering Lymph Nodes
- B-cells: Look for free antigens in lymph nodes.
- Lymph node macrophages: viruses and large antigens.
- Lymph fluid: soluble (small) antigens.
- T-cells: Look for DCs presenting antigens.
- Scan all DCs within 24 hours.
- If no antigen, move to next lymph node.
- If antigen detected, T-cell clones are activated.
- If soluble antigen detected, B-cells wait for Th cell activation.
B-Cell Activation
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If antigen detected, B-cell stays in lymph node.
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T-cells proliferate into Tc and Th cells (clonal selection).
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B-cell's IgD binds antigen, engulfs it, processes it, and presents it via MHC II.
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Within 48 hours, B-cell finds a Th cell with the correct TCR.
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B-cell is activated, differentiating into plasma cells.
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B-cell activation and proliferation take 4-7 days in lymph nodes, producing ~5000 plasma cells.
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Plasma cells produce 5 classes of antibodies (GAMED).
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Description
This quiz covers the crucial concepts of T-cell activation, including the role of the thymus, T-cell receptors, and recognition of antigens. You will learn about the different types of T-cells, their mechanisms, and the importance of MHC molecules in immune response. Test your knowledge on how these immune cells combat intracellular pathogens and tumors.
