Chapter 5

Question 1

thymus

Answer 1

primary lymphoid organ
T cell development

Question 2

thymocytes

Answer 2

immature T cells
development steps to ensure proper TCR expression in cortex of thymus

Question 3

inner medulla of thymus

Answer 3

mature thymocytes undergo negative selection and finish development into naive T cells

Question 4

cells of thymus

Answer 4

thymic epithelial cells (TECs)
macrophages
dendritic
hassall’s corpuscles

Question 5

lymphoid progenitors

Answer 5

precursors to several cell types
must receive appropriate signal to commit to differentiation

Question 6

notch signaling pathway

Answer 6

regulates proliferation and differentiation
cell-surface receptor that interacts with transmembrane ligands on adjacent cells

Question 7

double negative thymocyte

Answer 7

doesn’t express either coreceptor (CD4/CD8)
found in thymic cortex during initial development
begins somatic recombination at the TCR loci and continues until both subunits of the receptor have primarily rearranged

Question 8

double positive thymocyte

Answer 8

expresses a fully rearranged TCR and both CD4/CD8

Question 9

fates of a double positive thymocyte

Answer 9

regulatory T cell
NK T cell
process of positive and negative selection to test TCR and become a single positive thymocyte

Question 10

single positive thymocyte

Answer 10

expresses either CD4 or CD8

Question 11

thymocyte checkpoints

Answer 11

gamma and delta subunit of T cell receptor
beta subunit of T cell receptor, trial alpha subunits
alpha subunit of T cell receptor, made for real or it dies

Question 12

gamma and delta T cells

Answer 12

protect fetus during development

Question 13

gamma and delta T cells

Answer 13

protect fetus during development
protect mucosal surfaces in adults

Question 14

RAG1 RAG2 recombination

Answer 14

crossing over at beta/gamma/delta loci of TCR
most productive rearrangements will be beta-chain

Question 15

pre-T alpha chain (pTa)

Answer 15

surrogate alpha chain
assembles with rearranged beta chain and the CD3 complex to form the pre-TCR

Question 16

pre-T cell receptor complex

Answer 16

ensures functioning T cell receptor can signal via the same transduction pathways used to activate T cells
heavy chain with surrogate trying to make alpha

Question 17

beta checkpoint

Answer 17

proliferates
express RAG1 RAG2 again
begin recombination at other T cell receptor loci
allelic exclusion

Question 18

alpha chain testing

Answer 18

ensures TCR function
tested in ER membrane

Question 19

proper alpha chain

Answer 19

developing thymocyte continues development into a naive cell

Question 20

improper alpha chain

Answer 20

alpha chain locus further rearranged

Question 21

positive selection

Answer 21

promotes selection of thymocytes that can bind o self-MHC molecules
MHC restriction

Question 22

negative selection

Answer 22

prevents the release of thymocytes that can recognize MHC-self-peptide complexes with high affinity
self-tolerance

Question 23

first screen of double positive

Answer 23

double positive thymocytes interact with cortical thymic epithelial cells (cTECs) to test the affinity of the TCR with MHC-peptide complexes at the cell surface

Question 24

cTECs

Answer 24

express both MHC class I and II molecules
can present a variety of self-peptides to promote positive selection of double positive thymocytes-positively selecting those with the ability of the TCR to interact with MHC

Question 25

selection within thymic cortex

Answer 25

death by neglect negative selection positive selection

Question 26

death by neglect

Answer 26

double positive thymocytes cannot interact with any MHC peptide complexes

Question 27

negative selection of DP thymocytes

Answer 27

DP thymocytes bind too tightly with an MHC peptide complex