W2_04 T Cells

Question 1

which factors are important in a Th cell to turn a B cell into a plasma cell?

Answer 1

MHC complex (+CD4), CD40L, cytokines (IL-4,5,6)

Question 2

which 2 signals do macrophages need to be activated and digest phagocytosed contents?

Answer 2

IFN-gamma (from Th1);

CD40L from T cell onto CD40

Question 3

what are the two classes of TCRs? which is more common?

Answer 3

alpha:beta; (more common)

gamma;delta

Question 4

what is part of the TCR complex?

Answer 4

the TCR itself (alpha:beta),
CD3 complex (gamma, delta, epsilon, zeta),
CD4/CD8 co-receptor

Question 5

what are the gene components of the TCR recombination?

Answer 5

V and J

Question 6

how do T cells travel through lymphoid organs as they develop?

Answer 6

precursor goes from BM to thymus to mature;

T cells go to secondary lymphoid tissues

Question 7

what’s the difference in the specificity of the TCR and BCR?

Answer 7

BCR can bind to any exposed antigen.
TCR can only bind to specific segments of a protein, even those that are normally hidden by folding, so proteins need to be chopped up to be presented to T cells

Question 8

HLA A, B, C is which type of MHC class?

Answer 8

MHC class I (mnemonic: has 1 letter)

Question 9

HLA DP, DQ, DR is which type of MHC class?

Answer 9

MHC class II (mnemonic: has 2 letters)

Question 10

where do you find MHC class I molecules?

Answer 10

on all cells

Question 11

where do you find MHC class II molecules?

Answer 11

on APCs only

Question 12

what are the components of MHC class I?

Answer 12

3 alphas + 1 beta

Question 13

what are the components of MHC class II?

Answer 13

2 alphas + 2 beta

Question 14

note: MHC is stable and DO NOT REARRANGE

Answer 14

diversity is inherited; we can have up to 6

Question 15

CD8 cells match to which MHC?

Answer 15

MHC class I; CD8 on killer T cells

Question 16

CD4 cells match to which MHC?

Answer 16

MHC class II; CD4 on Th cells

Question 17

where does antigen bind to MHC I during preparation?

Answer 17

in the ER

Question 18

where does antigen bind to MHC II during preparation?

Answer 18

in the phagolysosome

Question 19

where are dendritic cells found in the thymus?

Answer 19

medulla

Question 20

where are cortical epithelial cells found in the thymus?

Answer 20

cortex

Question 21

how do T cells develop with their receptors?

Answer 21

beta, gamma, delta first.

then alpha, gamma, delta

Question 22

how do T cells move through the thymus as they mature?

Answer 22

start in the medulla. meet dendritic cells. move to cortex. and mature to double-negative near the surface. head back towards cortico-medullary junction and become mature double-positive cells.

Question 23

what is positive selection?

Answer 23

identifies T cells that can recognize self-MHC

Question 24

what is negative selection?

Answer 24

identifies T cells that recognize self antigens

Question 25

how do T cells have negative selection for tissues outside the thymus?

Answer 25

AutoImmune REgulator (AIRE) allows epithelial cells in the thymic medulla to secrete self Tissue Specific Antigens. so T cells that bind to these are negatively selected for.

Question 26

what is required for co-stimulation of T cells?

Answer 26

B7 must exist on the APC. this binds to CD28 on the T cell.

Question 27

what happens to the T cell w/o co-stimulation?

Answer 27

T cell becomes anergic

Question 28

what are the transcription factors for TCR and CD28?

Answer 28

NFAT and AP1

Question 29

which cytokine is responsible for T cell proliferation and differentiation?

Answer 29

IL-2. T cells have receptors AND produce it. causes burst of proliferation.

Question 30

which 2 mechanisms can CD8 cells kill?

Answer 30

lytic granules; | FasL-Fas interaction

Question 31

Th1 induced by?

Answer 31

IFN-gamma; IL-12

Question 32

Tfh induced by?

Answer 32

IL-6, IL-21

Question 33

Th2 induced by?

Answer 33

IL-4

Question 34

Th17 induced by?

Answer 34

IL-6, TGF-beta

Question 35

Treg induced by?

Answer 35

TGH-beta

Question 36

which two stimuli do macrophages need to be activated?

Answer 36

IFN-gamma; | CD40L

Question 37

what do Th1 cells do?

Answer 37

macrophage activation to fight intravesicular pathogens (e.g. bacteria + viruses)

Question 38

what do Th2 cells do?

Answer 38

B cell antibody production (IgA + IgE) for parasite and extracellular bacterial fighting

Question 39

why do granulomas form?

Answer 39

when the macrophage can't digest the material. there are giant cells, a bunch of macrophages, and a rim of T cells

Question 40

what are the cytotoxins of the T cell?

Answer 40

perforin and granulysin make pores in the target cell membrane, granzymes are the lytic granules

Question 41

what is leprosy?

Answer 41

an infection with mycobacterium leprae. bacteria infect the macrophages and aren't easily digested. thus, T cells polarized to Th1 response.

Question 42

how does tuberculid leprosy manifest?

Answer 42

slow damage to skin and peripheral nerves

Question 43

what is lepromatous leprosy?

Answer 43

bacteria grow unchecked outside the cells. T cells polarized to Th2. severe tissue destruction

Question 44

name some mechanisms of tolerance

Answer 44

negative selection in BM; anergy induction in autoreactive T and B cells; suppression of autoimmune responses by regulatory T cells; expression of tissue specific proteins in the thymus

Question 45

name 2 mechanisms of peripheral tolerance

Answer 45

anergy if they don't receive co-stimulation; | suppression by regulatory T cells

Question 46

which important transcription factor is associated with Treg cells?

Answer 46

Foxp3

Question 47

what are the two subsets of Treg cells?

Answer 47

natural (nTreg) from thymus; | inducible (iTreg) from peripheral naive T cells