Immunology #8 - T Cell And Cellular Response | Attempts: 236

2.

What is the cell-surface marker of the stem cell progenitor from which T cells of both lineages originate?

CD2
CD34
CD28
CD5

Correct Answer

A. CD34

Explanation

CD34 is the correct answer because it is a cell-surface marker that is expressed on the stem cell progenitors from which T cells of both lineages originate. CD34 is commonly used as a marker to identify and isolate hematopoietic stem cells, including those that give rise to T cells. It is not expressed on mature T cells, but its expression is critical during early T cell development. CD2, CD28, and CD5 are also cell-surface markers associated with T cells, but they are not specifically expressed on the stem cell progenitors from which T cells originate.

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3.

Where does positive selection of T cells take place

Bone marrow
Dendritic Cells
Thymus cortex
Secondary lymphoid tissue

Correct Answer

A. Thymus cortex

Explanation

Positive selection of T cells takes place in the thymus cortex. This is where immature T cells undergo a selection process to ensure that only T cells with functional T cell receptors (TCRs) are allowed to mature and leave the thymus. The thymus cortex provides an environment for T cells to interact with self-antigens presented by specialized cells called thymic epithelial cells. T cells that recognize self-antigens with moderate affinity undergo positive selection, which leads to their maturation and differentiation into functional T cells capable of recognizing foreign antigens.

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4.

On which cells is B7 expressed?

T cells
Dendritic cells
Cortical Epithelial cells
Thymocytes

Correct Answer

A. Dendritic cells

Explanation

Dendritic cells are the cells on which B7 is expressed. B7 is a co-stimulatory molecule that plays a crucial role in the activation of T cells. Dendritic cells are antigen-presenting cells that capture, process, and present antigens to T cells, thus initiating an immune response. By expressing B7, dendritic cells provide the necessary co-stimulation to T cells, leading to their activation and subsequent immune response. Therefore, dendritic cells are essential for the initiation and regulation of immune responses.

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5.

What cells suppress autoreactive T cells?

T regulatory cells
Dendritic cells
B cells
Cortical epithelial cells

Correct Answer

A. T regulatory cells

Explanation

T regulatory cells, also known as Tregs, are specialized immune cells that play a crucial role in suppressing autoreactive T cells. Autoreactive T cells are immune cells that mistakenly target and attack the body's own cells and tissues, leading to autoimmune diseases. Tregs help maintain immune tolerance by suppressing the activation and proliferation of autoreactive T cells, thus preventing the development of autoimmune responses. They do this through various mechanisms, including the secretion of immunosuppressive molecules and direct cell-to-cell contact. Overall, T regulatory cells are essential in preventing harmful immune responses and maintaining immune homeostasis.

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6.

Which of these molecules directly drives proliferation of T cells?

MHC
IFN
IL-2
IL-4

Correct Answer

A. IL-2

Explanation

IL-2 directly drives proliferation of T cells. IL-2 is a cytokine that is produced by activated T cells and plays a crucial role in regulating immune responses. It acts as a growth factor for T cells, promoting their proliferation and survival. IL-2 binds to IL-2 receptors on the surface of T cells, triggering a signaling cascade that leads to cell division and expansion of the T cell population. This cytokine is essential for the immune system's ability to mount an effective immune response against pathogens and tumors.

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7.

What happens when the co-stimulatory response is activated (i.e. B7 + CD28) without the binding of the MHC:peptide complex?

Tolerance
Autoreactive immune response
T cell activation
No effect on T cell

Correct Answer

A. No effect on T cell

Explanation

When the co-stimulatory response is activated without the binding of the MHC:peptide complex, it means that the T cell receptor (CD28) is not being engaged by the antigen-presenting cell. In this case, there will be no effect on the T cell because the co-stimulatory signal alone is not sufficient to activate the T cell. The binding of the MHC:peptide complex is necessary for T cell activation, so without it, the T cell will not be activated.

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Immunology #8 - T Cell And Cellular Response

The "double negative" contains

Quiz Preview

What is the cell-surface marker of the stem cell progenitor from which T cells of both lineages originate?

Where does positive selection of T cells take place

On which cells is B7 expressed?

What cells suppress autoreactive T cells?

Which of these molecules directly drives proliferation of T cells?

What happens when the co-stimulatory response is activated (i.e. B7 + CD28) without the binding of the MHC:peptide complex?