Immunology Chapter 7 The Development of T Lymphocytes

One function of _________ is to remove the _____ that fail to mature properly.

macrophages; thymocytes

The _________ consists of immature thymocytes, branched cortical epithelial cells and a few macrophages.

cotex

The _________ consists of mature thymocytes, medullary epithelial cells, dendritic cells and macrophages.

medulla

Condition where the thymus gland, a crucial organ for immune system development is underdeveloped or absent.

Thymic Hypoplasia

When progenitor cells enter the thymus they are called _______________ because they do not express ______ or _______.

double-negative thymocytes (DN thymocytes); CD4; CD8

After VDJ rearrangement cells that fail to make productive T-cell receptor gene rearrangements die by apoptosis and are phagocytosed by macrophages in the thymic cortex. At this stage ⍺:β T-cells are _______________ expressing _____ and _________ on the cell surface.

double positive; CD4; CD8

Pre-T-cell receptor consists of ______ chain asscoaited with a _________ chain called _____.

TCRβ; surrogate ⍺; pT⍺

_____ and _____ signaling initiate rearrangement of the ______ and stops the production of ______.

CD3; 𝜻 (zeta); ⍺-chain; pT⍺

Positive selection of T cells in the thymus applies only to αβ T cells, not γδ T cells. Both MHC class I and II present peptides from protein turnover. If a ___________ complex is bound within ________ after the thymocyte first expresses a functional receptor then a signal is received by the thymocyte that enable its further maturation.

peptide:MHC; 3-4 days

During positive selection, interaction of the T-cell receptor with a peptide presented by MHC class II or MHC class I determines whether the T cell commits to the CD4 or the CD8 T-cell lineage.

T-cell commitment

Tight binding T cells are potentially autoreactive and, if allowed to enter the peripheral circulation, could damage tissue and cause autoimmune disease.

Negative selection of T cells in the thymus

Regulatory T cell (T regs
Expression of CD25 on the cell surface and the unique use of a transcriptional repressor protein called _____ suppresses the activation and proliferation of ______ responding to self antigens.

FoxP3; naive T-cells

Order of T-cell development stages

1. Proliferation and differentiation to double positive CD3+ thymocytes

2. Positive Selection

3. Negative Selection

4. Entry to the Circulation

The thymus becomes larger as we age.

True