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immunology > T Cell Receptor and T lymphocyte development > Flashcards

T Cell Receptor and T lymphocyte development Flashcards

1
Q

what is matruation of early thymocyte

A

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

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2
Q

what is maturation of common thymocyte

A

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

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3
Q

what is maturation of mature thymocyte

A

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

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4
Q

what does positive and negative selection do

A

most self- reactive T cells are eliminated

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5
Q

All T cells are positive for

A

TCR ,CD2, CD3, CD28

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6
Q

What are the two antigen-specific TCR dimers

A

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

gamma-delta ( this is the rest of them)

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7
Q

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

A

beta and gamma chains

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8
Q

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

A

alpha and delta chains

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9
Q

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

A

receptors to activate the T cell;

CD3 association initiates signal transduction

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10
Q

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

A

variable region
constant region
heterodimer binding site of two different chains

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11
Q

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

A

from bone marrow ==>thymus

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

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12
Q

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

A

CD4, CD8, and NKT cells

in thymus

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13
Q

mature T cells circulate where? until?

A

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

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14
Q

When T cells hit the dendritic cells, what happens

A

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

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15
Q

what are some bone marrow derived cells in thymus

A

macrophage,
dendritic cell,
thymocyte

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16
Q

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

A

cortical epithelial cell, ( in the cortex of thymus )

medullary epithelial cell ( in the medulla of thymus )

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17
Q

what thymocytes are in the cortex of thymus

A

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

aka immature thymocytes

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18
Q

what thymocytes are in the medulla of the thymus

A

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

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19
Q

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

A

hassal’s corpuscle ( the onion looking thing )

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20
Q

what is CD34 for?

A

stem-cell surface marker;

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21
Q

what is CD2 for?

A

adhesion and signaling

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22
Q

what is CD5 for

A

adhesion and signaling

23
Q

what is IL-7 ( CD127 for)

A

a cytokine recedptor

24
Q

what is CD44 for?

A

adhesion;

25
Q

what is CD1A for

A

MHC class 1 - like molecule

26
Q

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

A

CD 34 and CD 44

27
Q

why do t cells only mature in the thymus

A

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

28
Q

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

A

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

29
Q

what enzyme is NECCESSARY for gene rearrangement

A

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

30
Q

how do you get junctional diversity

A

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.

31
Q

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

A

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

32
Q

successful rearrangement of one beta copy ____

A

blocks the beta copy on the other chromosome

33
Q

successful rearragement of one alpha copy ____

A

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

34
Q

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

A

you get a gamma delta t cell

35
Q

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

A

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

36
Q

where is the delta chain locus

A

inside the alpha chain locus

37
Q

what do gamma delta t cells do?

A

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

38
Q

CD8 binds

A

MHC class 1

39
Q

CD4 binds

A

MHC class 2

40
Q

gamma delta t cells recognize

A

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

41
Q

gamma delta t cells don’t have to

A

… they recognize antigens even if they aren’t presented on MHC molecules

42
Q

CD8 t cells kill

A

cells infected with intracellular pathogens or tumor cells

43
Q

CD4 T cells regulate

A

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

44
Q

how many pieces are in a CD 4

A

there are 4 subunits that make

45
Q

antigen specificity determines its fate. what does that mean?

A

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

46
Q

what is the first stage of T cell hazing

A

positive selection

47
Q

what happens during the first stage of T cell hazing

A

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

48
Q

what is the second stage of Tcell hazing

A

this is negative selection

49
Q

what happens during the second stage of T cell hazing

A

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

50
Q

Igs act as?

A

receptors and effector molecules

51
Q

what can cause ineffective negative selection?

A

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

52
Q

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

A

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.

53
Q

what is the best number of MHC isotypes to express

A
  1. this way you get the most number of well selected T cells
54
Q

Di George’s syndrome - 2 things

A

no or few T cells because of a lacking or small thymus;

symptoms are similar to SCID patients

immunology (9 decks)

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