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Questions and Answers
Which leukocytes are primarily responsible for antigen presentation?
Which leukocytes are primarily responsible for antigen presentation?
Where do T cells originate?
Where do T cells originate?
What is the primary function of B cells in the adaptive immune response?
What is the primary function of B cells in the adaptive immune response?
During their maturation, T cells undergo which process in the thymus?
During their maturation, T cells undergo which process in the thymus?
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Which statement correctly describes the relationship between T-helper cells and B cells?
Which statement correctly describes the relationship between T-helper cells and B cells?
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What occurs to immature T-cells after they leave the bone marrow?
What occurs to immature T-cells after they leave the bone marrow?
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Where do mature T cells reside after leaving the thymus?
Where do mature T cells reside after leaving the thymus?
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Neutrophils are considered antigen presenting cells to a lesser extent than which of the following?
Neutrophils are considered antigen presenting cells to a lesser extent than which of the following?
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What is primarily activated by antigen presenting cells?
What is primarily activated by antigen presenting cells?
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What type of immunity are T lymphocytes primarily associated with?
What type of immunity are T lymphocytes primarily associated with?
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What is the primary function of cytotoxic T-cells (TC cells) in the immune response?
What is the primary function of cytotoxic T-cells (TC cells) in the immune response?
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During central tolerance, what happens to T-cells and B-cells that react with self-antigens?
During central tolerance, what happens to T-cells and B-cells that react with self-antigens?
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Which step in the mechanism of TC cells involves the production of perforin?
Which step in the mechanism of TC cells involves the production of perforin?
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What role do TH cells play in the activation of B cells?
What role do TH cells play in the activation of B cells?
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What is the main purpose of B-cell proliferation during a humoral immune response?
What is the main purpose of B-cell proliferation during a humoral immune response?
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What is the function of granzyme B in the mechanism of cytotoxic T cells?
What is the function of granzyme B in the mechanism of cytotoxic T cells?
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Which type of immunity is primarily mediated by antibodies in response to a pathogen?
Which type of immunity is primarily mediated by antibodies in response to a pathogen?
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Which component is crucial for the establishment of immunological memory during a secondary immune response?
Which component is crucial for the establishment of immunological memory during a secondary immune response?
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What is the role of regulatory T cells (TR cells) in the immune response?
What is the role of regulatory T cells (TR cells) in the immune response?
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What happens when B cells differentiate into plasma cells?
What happens when B cells differentiate into plasma cells?
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Study Notes
Activation of the Adaptive Immune Response
- Antigen Presenting Cells (APCs) include macrophages, dendritic cells, and neutrophils, crucial for activating the adaptive immune response.
- APCs phagocytize foreign pathogens and present their antigens to invoke an immune reaction.
Lymphocytes
- Lymphocytes are white blood cells found in blood and the lymphatic system, primarily consisting of two types: T cells and B cells.
- T cells kill pathogens and activate B cells; they are formed in the bone marrow and mature in the thymus.
- B cells produce antibodies and form memory cells, originating and maturing in the bone marrow.
T Lymphocytes and Cell-Mediated Immunity
- T cells originate in the bone marrow and mature in the thymus where they undergo clonal deletion.
- Mature T cells circulate in the blood and lymphatic tissues; clonal deletion ensures self-tolerance by eliminating cells that react to self-antigens.
- Central tolerance occurs during maturation; peripheral tolerance refers to clonal deletion of immature cells responding to self-antigens.
Steps of T-Cell Action
- Neutrophils and macrophages phagocytose pathogens and present antigens to T-helper cells (TH cells).
- Activation of TH cells leads to stimulation of cytotoxic T cells (TC), memory T cells, and B cells; they produce cytokines to enhance immune response.
- TC cells directly kill infected cells, while TM cells provide long-term immunity.
- Regulatory T cells (TR) prevent autoimmunity by regulating the immune response.
- B cells synthesize antibodies targeted against specific pathogens.
Mechanism of Cytotoxic T Cells
- TC cells induce apoptosis in virus-infected cells through several mechanisms.
- TC cells bind to infected cells via MHC molecules, producing perforins that create pores in target cell membranes.
- Granzyme enzymes enter through these pores; granzyme A poisons the cell, and granzyme B destroys it.
- Apoptosis is initiated by the binding of the TC cell's Fas ligand to the Fas receptor on the target cell.
- Interferons are released to inhibit viral replication and enhance the immune response in neighboring cells.
- Antibodies act on released viruses during and after the apoptotic event, opsonizing them to prevent further infection.
B-Cells and Humoral Immunity
- Each B cell is specific to a unique antigen; TH cells activate these specific B cells.
- Activated B cells undergo clonal expansion, rapidly proliferating to fight the infection.
- During clonal expansion, B cells differentiate into plasma cells or memory B cells.
- Plasma B cells produce antibodies during the primary immune response; they are short-lived.
- Memory B cells provide rapid antibody production during secondary infections, underpinning immunological memory, which facilitates faster and more effective responses upon re-exposure to the same pathogen.
- Humoral immunity relies on antibodies found in bloodstream and lymphatic fluid, central to the body’s defense mechanism.
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Description
This quiz covers the activation of the adaptive immune response, focusing on Antigen Presenting Cells (APCs), lymphocytes including T cells and B cells, and their roles in immunity. Understand how these cells work together to defend against pathogens and the processes of self-tolerance in T cell maturation.
