MICR223_23_T cell effectors

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.