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What is the primary function of cytotoxic T cells?
What is the primary function of cytotoxic T cells?
Which type of T cell has CD4 as a coupling protein for the antigen-MHC complex?
Which type of T cell has CD4 as a coupling protein for the antigen-MHC complex?
What is the significance of clonal selection in the immune response?
What is the significance of clonal selection in the immune response?
Which of the following is true about activated B cells?
Which of the following is true about activated B cells?
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What is the role of cytokines in the immune response?
What is the role of cytokines in the immune response?
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How do antigens signal an infected cell for immune response?
How do antigens signal an infected cell for immune response?
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What is the role of activated helper T cells in the immune response?
What is the role of activated helper T cells in the immune response?
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Which protein do inactive helper T cells bind to when recognizing the MHC-antigen complex on an antigen-presenting cell?
Which protein do inactive helper T cells bind to when recognizing the MHC-antigen complex on an antigen-presenting cell?
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What is the main function of active cytotoxic T cells in the immune response?
What is the main function of active cytotoxic T cells in the immune response?
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What is the primary mechanism by which activated cytotoxic T cells kill infected target body cells?
What is the primary mechanism by which activated cytotoxic T cells kill infected target body cells?
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After activation, what is the fate of helper T cells during clonal selection?
After activation, what is the fate of helper T cells during clonal selection?
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Which type of cell recognizes the MHC-antigen complex on infected or abnormal body cells?
Which type of cell recognizes the MHC-antigen complex on infected or abnormal body cells?
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Which type of immunity involves Cytotoxic T cells directly attacking invading antigens?
Which type of immunity involves Cytotoxic T cells directly attacking invading antigens?
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What is the main function of activated B cells in the immune response?
What is the main function of activated B cells in the immune response?
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In adaptive immunity, what is the process by which a lymphocyte divides and differentiates into a clone of cells?
In adaptive immunity, what is the process by which a lymphocyte divides and differentiates into a clone of cells?
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Which type of immunity is mainly effective against extracellular pathogens, including viruses, bacteria, and fungi?
Which type of immunity is mainly effective against extracellular pathogens, including viruses, bacteria, and fungi?
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What is the role of effector cells in the immune response?
What is the role of effector cells in the immune response?
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Which type of immune cells have a long life span and can divide to form more effector and memory cells upon re-exposure to the same antigen?
Which type of immune cells have a long life span and can divide to form more effector and memory cells upon re-exposure to the same antigen?
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What is the initial step in the antibody-mediated immune response?
What is the initial step in the antibody-mediated immune response?
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During clonal selection, which types of cells do activated B cells differentiate into?
During clonal selection, which types of cells do activated B cells differentiate into?
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Which immunoglobulin class is involved in disabling antigens for destruction by other immune actions?
Which immunoglobulin class is involved in disabling antigens for destruction by other immune actions?
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What stimulates a more intense B cell response in the antibody-mediated immune response?
What stimulates a more intense B cell response in the antibody-mediated immune response?
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Which process leads to the production of plasma cells in the antibody-mediated immune response?
Which process leads to the production of plasma cells in the antibody-mediated immune response?
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What is the main biological role of plasma cells in the immune response?
What is the main biological role of plasma cells in the immune response?
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What is the primary function of cytotoxic T cells?
What is the primary function of cytotoxic T cells?
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Which type of immunity involves mainly targeting extracellular pathogens like viruses and bacteria?
Which type of immunity involves mainly targeting extracellular pathogens like viruses and bacteria?
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During clonal selection, what is the fate of memory cells?
During clonal selection, what is the fate of memory cells?
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What happens to activated B cells in the immune response?
What happens to activated B cells in the immune response?
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Which process occurs when a lymphocyte divides and differentiates into a clone of cells with the same specificity to an antigen?
Which process occurs when a lymphocyte divides and differentiates into a clone of cells with the same specificity to an antigen?
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What is the main function of effector cells in the immune response?
What is the main function of effector cells in the immune response?
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What distinguishes adaptive immunity from innate immunity?
What distinguishes adaptive immunity from innate immunity?
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Where do B cells complete their development?
Where do B cells complete their development?
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What is the main role of cytotoxic T cells in the immune response?
What is the main role of cytotoxic T cells in the immune response?
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During clonal selection, what happens to lymphocytes?
During clonal selection, what happens to lymphocytes?
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Which protein is inserted by T cells to facilitate coupling with antigen-presenting cells?
Which protein is inserted by T cells to facilitate coupling with antigen-presenting cells?
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What is the primary function of activated B cells in the immune response?
What is the primary function of activated B cells in the immune response?
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Study Notes
Helper T Cells and APCs
- Inactive helper T cells recognize MHC-antigen complex on antigen-presenting cells and bind with CD4 protein.
- If costimulation occurs, activated helper T cells undergo clonal selection into active and memory helper T cells.
- Active helper T cells respond within hours of costimulation by secreting cytokines, acting as a costimulator for other T cells, and enhancing proliferation of B cells and natural killer cells.
Cytotoxic T Cells and Body Cells
- Inactive cytotoxic T cells recognize MHC-antigen complex on infected or abnormal body cells and bind with CD8 protein.
- If costimulation occurs, activated cytotoxic T cells undergo clonal selection into active and memory cytotoxic T cells.
- Active cytotoxic T cells leave lymphatic tissue and secrete substances to kill infected target body cells, including:
- Granzymes, which trigger apoptosis of target cells.
- Perforin, which causes cell membrane cytolysis of target cells.
- Granulysin, which destroys intracellular microbes.
- Lymphotoxin, which fragments target cell DNA.
Types of Adaptive Immunity
- Cell-mediated immunity, which is effective against pathogens, cancer cells, and transplant tissues, involving cytotoxic T cells directly attacking invading antigens.
- Antibody-mediated immunity, which is mainly effective against extracellular pathogens, including viruses, bacteria, and fungi, involving activated B cells transforming into plasma cells that synthesize and secrete specific antibodies.
Adaptive Immunity
- Clonal selection is the process by which a lymphocyte divides and differentiates into a clone of cells that can recognize the same specific antigen as the original activated cell.
- Two major types of cells are produced from the clone:
- Effector cells, which carry out the immune response to destroy or inactivate antigen-bearing substances.
- Memory cells, which do not participate in the current immune response and have a long lifespan, dividing and differentiating into more effector and memory cells if the same antigen is encountered in the future.
Processing and Presentation of Antigens
- Processing of endogenous antigens involves infected cells having antigens inside the cell, including viral proteins, bacterial toxins, and abnormal proteins synthesized by cancerous cells.
- Fragments of antigen bind to MHC and are inserted into the cell membrane, signaling as an infected cell for immune response.
Cytokines
- Cytokines are small hormones that stimulate or inhibit many normal cell functions, such as growth and differentiation.
- They are secreted by lymphocytes and antigen-presenting cells for immune response.
Cell-Mediated Immune Response
- Begins with the activation of a small number of T cells by a specific antigen.
- Helper T cells with CD4 and cytotoxic T cells with CD8 have different coupling proteins for antigen-MHC complex.
- Activated T cells undergo clonal selection into active and memory T cells.
Antibody-Mediated Immune Response
- Begins with the activation of B cells by a specific antigen.
- B cells can respond to unprocessed antigens, and costimulation by helper T cell cytokine after forming an antigen-MHC complex in their own cell membrane produces a more intense response.
- Activated B cells undergo clonal selection into plasma cells and memory B cells, with plasma cells secreting antibodies specific to the antigen.
Antibodies
- Antibodies are globulin plasma glycoproteins (immunoglobulins) that form an antigen-antibody complex with a specific complementary antigen epitope.
- There are 5 classes of antibodies based on chemistry and structure, each with its own biological role:
- IgG
- IgA
- IgM
- IgD
- IgE
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Description
Learn about the interaction between helper T cells and antigen presenting cells (APCs). Understand the process of activation and function of helper T cells, including clonal selection and cytokine secretion.
