T Cell Receptor and T lymphocyte development

Question 1

what is matruation of early thymocyte

Answer 1

CD 4- 8-; Tcell receptor (TCR) gene rearrangements

Question 2

what is maturation of common thymocyte

Answer 2

CD 4+ 8+ ; T cell receptor gene rearrangements; low TCR and CD3 surface expression

Question 3

what is maturation of mature thymocyte

Answer 3

has a CD 4+ or CD 8+ subset; high TCR and CD3 surface expression; there is somatic recombination of TCR genes

Question 4

what does positive and negative selection do

Answer 4

most self- reactive T cells are eliminated

Question 5

All T cells are positive for

Answer 5

TCR ,CD2, CD3, CD28

Question 6

What are the two antigen-specific TCR dimers

Answer 6

alpha-beta (this is 90-95% of them)

gamma-delta ( this is the rest of them)

Question 7

what chains are from the V, D, J, and C genes

Answer 7

beta and gamma chains

Question 8

what chains are made from the V, J, and C genes

Answer 8

alpha and delta chains

Question 9

what is the whole point of the TCR? what does it complex with

Answer 9

receptors to activate the T cell;

CD3 association initiates signal transduction

Question 10

if we compare the two classes of the T cell receptors: both have

Answer 10

variable region
constant region
heterodimer binding site of two different chains

Question 11

T cells move from where to where to where (organs)

Answer 11

from bone marrow ==>thymus

thymus ==> lymph node, spleen, gut associated lymph

Question 12

T cell progenitor cells differetiate into __ (3)? where?

Answer 12

CD4, CD8, and NKT cells

in thymus

Question 13

mature T cells circulate where? until?

Answer 13

circulate between blood and lymph tissue until they recognize antigens presented on dendritic cells in lymph tissue

Question 14

When T cells hit the dendritic cells, what happens

Answer 14

they further mature to become either functional memory T cell or effector T cell

Question 15

what are some bone marrow derived cells in thymus

Answer 15

macrophage,
dendritic cell,
thymocyte

Question 16

what are some thymic derived cells in the thymus? where are they?

Answer 16

cortical epithelial cell, ( in the cortex of thymus )

medullary epithelial cell ( in the medulla of thymus )

Question 17

what thymocytes are in the cortex of thymus

Answer 17

[CD4- CD8-], [CD4+ CD8+]

aka immature thymocytes

Question 18

what thymocytes are in the medulla of the thymus

Answer 18

[CD4+ CD8-], [CD8+, CD4-]

Question 19

whats a histo thing that you shouldn’t forget in the thymus

Answer 19

hassal’s corpuscle ( the onion looking thing )

Question 20

what is CD34 for?

Answer 20

stem-cell surface marker;

Question 21

what is CD2 for?

Answer 21

adhesion and signaling

Question 22

what is CD5 for

Answer 22

adhesion and signaling

Question 23

what is IL-7 ( CD127 for)

Answer 23

a cytokine recedptor

Question 24

what is CD44 for?

Answer 24

adhesion;

Question 25

what is CD1A for

Answer 25

MHC class 1 - like molecule

Question 26

what two marker and/or adhesion components are on uncommitted progenitor cells

Answer 26

CD 34 and CD 44

Question 27

why do t cells only mature in the thymus

Answer 27

the thymic epithelium have a notch ligand which binds to the notch 1 marker on a thymocyte. the binding cleaves the notch 1 intracellular domain and starts a downstream signal to start transcription in the nucleus

Question 28

when the TCR rearranges DNA in the thymus, what does it do first and then (beta gene rearrangement)

Answer 28

in the beta, it combines the D and J then it does the VDJ rearrangement.

Question 29

what enzyme is NECCESSARY for gene rearrangement

Answer 29

RAG - it cleaves the gene and adds some nucleotides to make a sticky end where it just cut

Question 30

how do you get junctional diversity

Answer 30

the RAG cleaves and makes a sticky end; when the gwo genes are hybridized, the sticky ends don't always COMPLETELY overlap; you get some extra spots that look like okasaki fragments and those are filled in this creates diversity.

Question 31

Ok so the beta chain has gene rearrangement first. what does the beta chain signal after it is created

Answer 31

it is expressed on the surface along with a surrogate alpha chain; the beta gene rearrangement stops and the cell proliferates

Question 32

successful rearrangement of one beta copy ____

Answer 32

blocks the beta copy on the other chromosome

Question 33

successful rearragement of one alpha copy ____

Answer 33

does NOT block the alpha copy on the other chromosome; THEREFORE, it can express two different alpha chains

Question 34

if there is successful gene rearrangement in gamma and delta before beta, what happens

Answer 34

you get a gamma delta t cell

Question 35

if you have successful gene rearrangment in beta before gamma or delta, what happens

Answer 35

you get a pre-alpha beta t cell. its not committed yet. it will enter a phase of proliferation

Question 36

where is the delta chain locus

Answer 36

inside the alpha chain locus

Question 37

what do gamma delta t cells do?

Answer 37

they are always on and have anti-bacterial/viral/tumor functions

Question 38

CD8 binds

Answer 38

MHC class 1

Question 39

CD4 binds

Answer 39

MHC class 2

Question 40

gamma delta t cells recognize

Answer 40

small microbial compounds, most MHC class 1(ish) when the host is changed or stressed non protein alkylamines heat shock proteins

Question 41

gamma delta t cells don't have to

Answer 41

... they recognize antigens even if they aren't presented on MHC molecules

Question 42

CD8 t cells kill

Answer 42

cells infected with intracellular pathogens or tumor cells

Question 43

CD4 T cells regulate

Answer 43

(activate OR suppres) other immune cells like B cells, macrophages and tissue cells

Question 44

how many pieces are in a CD 4

Answer 44

there are 4 subunits that make

Question 45

antigen specificity determines its fate. what does that mean?

Answer 45

if the T cell receptor interacts with an Ag:MHCI, then it is defined as a CD8+ cell.

Question 46

what is the first stage of T cell hazing

Answer 46

positive selection

Question 47

what happens during the first stage of T cell hazing

Answer 47

this positive selection makes sure that the Tcell recognizes the self MHC complex; this makes ensures that the T cell will be loyal, and won't start hitting for the other team

Question 48

what is the second stage of Tcell hazing

Answer 48

this is negative selection

Question 49

what happens during the second stage of T cell hazing

Answer 49

this eleiminates auto-reactive T cells; aka Tcells that strongly bind to self antigen/MHC complex

Question 50

Igs act as?

Answer 50

receptors and effector molecules

Question 51

what can cause ineffective negative selection?

Answer 51

if the thymus self antigens are not expressined in the thymus, then the T cells can't be negatively selected and you get T cells in circulation that will improperly attack self cells

Question 52

what is the relationship between number of MHC molecules, positive T cell selection, and negative T cell selection

Answer 52

as the number of MHC INCREASES, the # of positively selected cells that survive INCREASES by N times, while the number of negatively selected (killed cells) DECREASES by N times.

Question 53

what is the best number of MHC isotypes to express

Answer 53

13. this way you get the most number of well selected T cells

Question 54

Di George's syndrome - 2 things

Answer 54

no or few T cells because of a lacking or small thymus; | symptoms are similar to SCID patients