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What are the learning objectives related to T cells in the MICR223 course?
To describe how CD4 and CD8 T cells control immune responses to pathogens and to discuss mechanisms of cell killing by the immune system.
What are the three main characteristics of T cells during an immune response?
Inducibility, specificity, and memory.
What is the role of CD4+ T cells in the immune response?
They act as helper T cells, making cytokines, improving function of antigen presenting cells, and supporting antibody production by B cells.
What is the primary function of CD8+ T cells?
They are killer T cells responsible for killing infected cells.
How do T cells become activated?
T cells get activated by recognizing MHC/peptide complexes.
What is clonal expansion in T cells?
The process where T cells proliferate in response to an antigen.
What cytokine is crucial for T cell proliferation?
IL-2.
What are cytokines?
Soluble inter-cellular signaling molecules released by living cells that regulate cell function.
How do cytokines affect T cells during an immune response?
Cytokines activate T cells, which then produce more cytokines.
What role do macrophages play concerning cytokines?
Macrophages respond to cytokines produced by activated T cells to enhance inflammatory responses.
How do CD4+ T cells assist in activating B cells?
CD4+ T cells produce cytokines that help B cells activate and differentiate into plasma cells.
What is the specific cytokine produced by Th1 cells?
IFN-y (Interferon gamma).
Which cytokine is produced by Th2 cells?
IL-4.
What role does IL-23 play in Th17 immune responses?
IL-23 stimulates T cells to produce IL-17, activating neutrophils and aiding in healing.
What is antibody class switching?
A process where B cells change the class of antibody they produce, influenced by cytokines.
What are T Follicular Helper Cells (TFh)?
TFh cells provide cytokines to B cells in follicles and help dictate the heavy chain class of antibodies produced.
What triggers the cytotoxicity of CD8+ T cells?
Recognition of infected cells through MHC-I and the release of perforins and granzymes.
What is the mechanism of perforin/granzyme-mediated cytotoxicity?
Perforin creates pores in infected cells, allowing granzymes to enter and activate apoptotic pathways.
What does Fas-mediated cytotoxicity involve?
The binding of FasL from T cells to Fas on target cells, triggering apoptosis through the caspase pathway.
What is cytokine-mediated cytotoxicity?
Activation of the caspase pathway in infected cells by cytokines like TNF-alpha and IFN-y produced by CD8+ T cells.
What is the role of IL-12 in T cell differentiation?
IL-12 binds to T cells to stimulate the production of IFN-y, promoting Th1 responses.
Which cytokines do CD4+ T cells produce in response to IL-4 stimulation?
IL-4, IL-5, and IL-13.
What is a hallmark of Th17 cytokine responses?
Stimulating the production of IL-17 for neutrophil activation.
What happens to B cells in germinal centers?
B cells with high affinity for antigens are selected for and proliferate, influenced by cytokines from TFh cells.
What pathway acts as a positive feedback loop in T cell activation?
The IL-2 pathway where IL-2 production leads to the expression of IL-2 receptors on T cells.
What are the clinical implications of different T cell populations?
Different T cell populations respond differently to pathogens, which can influence the course of autoimmune diseases.
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