Chapter 5 Quiz

. Of the following resident cells of the thymus, which does NOT drive the development of thymocytes into naïve T cells.

Dendritic cells

Macrophages

Thymic epithelial cells

Natural killer cells

. Which of the following statements are true about thymic cells?

They are essential to the selection events required to ensure tolerance.

They prevent the expression of the thymic stromal lymphopoietin (TSLP) protein.

They enter the thymus as single-positive (SP) T cells.

. How are lymphoid progenitors that migrate from the bone marrow to the thymus distinguished from other cells?

By the secretion of the thymic stromal lymphopoietin (TSLP) protein

By activation of the transcription factor FOXP3

By the secretion of IL-7 as a signaling molecule

By the cell-surface molecules that they express

. How does the activation of Notch1 occur within progenitor cells?

Through the secretion of interleukin-7 (IL-7) by thymic epithelial cells

By presentation of self-antigens by thymic epithelial cells in the thymus

Through the proteolytic cleavage of Notch1 in the lymphoid progenitor

By preventing the release of an the intracellular domain

. Identify the FALSE statement about γδ T cells.

They are the first T cells produced and work to protect the fetus.

They undergo the process of positive and negative selection to test the T-cell receptor and select for a single coreceptor.

They typically do not express the coreceptors CD4 or CD8 and therefore are double-negative T cells.

They play an important role in protecting mucosal surfaces.

. Which of the following is true if the β subunit recombines properly at the checkpoint of the β subunit of the T-cell receptor?

Recombination events at the α, γ, and δ T-cell receptor genes are inactivated.

A developing thymocyte becomes a γδ T cell and does not need to pass any further checkpoints

Somatic recombination is inactivated to allow the thymocyte to ready itself for the next developmental stage.

Rearrangement of the T-cell receptor loci begins at the β, γ, and δ genes.

. Which of the following is a protein expressed in thymocytes that has finished β-chain rearrangement and acts as a surrogate to test proper expression and action of the recombined β chain?

RAG1

Thymic stromal lymphopoietin (TSLP)

Notch1

Pre-T α chain (pTα)

. Which of the following refers to thymocytes that have successfully passed the β-chain checkpoint?

Single-positive thymocytes

DN4 cells

Pre-T cells

Double-positive thymocytes

. Which of the following terms refers to the inactivation of somatic recombination and active chromatin remodeling in order to prevent further recombination of specific loci of adaptive immune receptors?

Central tolerance

MHC restriction

Allelic exclusion

Lineage commitment

. Identify a consequence of the failure of the negative selection process of CD4+ thymocytes by dendritic cells in thymic medulla.

It can result in the absence of intraepithelial lymphocytes.

It limits the circulation of self-reactive T cells within an organism.

It can lead to autoimmune disorders in the individual.

It causes lymphoid progenitors in the thymus to develop into B cells rather than T cells.

. Which of the following is true of the T cells that express an αβ T-cell receptor?

These cells express an αβ T-cell receptor that behaves like a pattern recognition receptor of the innate immune system.

These cells constitute a small subset of T cells in the human body.

These cells reside mainly within the gut mucosa as intraepithelial lymphocytes.

When activated, these cells can differentiate into effector T cells that activate a range of immune responses.

. Identify the factor that does NOT contribute to T-cell receptor diversity.

The sheer number of V, D, and J subunits present for all chains associated with the T-cell receptor

Random recombination of variable segments

Chromatin remodeling by repackaging of the β-chain locus into tightly condensed chromatin

Junctional diversity by the addition and removal of P and N nucleotides during recombination

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