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DMD 5244 (Immunity) > Adaptive immunity Cell-Mediated (complete) > Flashcards

Adaptive immunity Cell-Mediated (complete) Flashcards

1
Q

what is the B-cell antigen receptor

A

a membrane bound immunoglobin (two heavy chains, two light chains)

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2
Q

what kinds of regions do the B and T cell antigen receptors have

A

proximal constant regions, and variable distal regions

just like antibodies

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3
Q

what is DiGeorge syndrome

A

when an individual has no T-cells, subject to many overwhelming infections

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4
Q

how are naive T cells activated

A

coming into contact with mature activated dendritic cells that have their MHC/antigen complex and lots of B7 molecules

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5
Q

what happens once a T-cell is activated

A

they proliferate and differentiate into effector T-cells that destroy or eliminate the antigen once they come into contact with it again

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6
Q

the first signal a T-cell needs to become activated is

A

the binding of the MHC/Antigen complex binding to the T-cell antigen receptor from a dendritic cell

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7
Q

the second signal that a T-cell needs to become activated is…

A

costimulatory signal

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8
Q

what are the most important costimulatory factors that assist in the activation of T-cells

A

B7-1 and B7-2 on dendritic cells, interacting with CD28 on T-cells

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9
Q

What is the function of T-helper cells

A

activate antigen producing B-cells
recruit and activate phagocytes
activate eosinophils, basophils and mast cells

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10
Q

What happens to the T-cells once the immune response has ended

A

they must return to normal levels (controlled by cytokines)

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11
Q

does the T-cell receptor (TCR) have cytoplasmic tails with any function

A

their cytoplasmic tails have no signaling function

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12
Q

since the cytoplasmic tails of TCR have no signaling function, how does the TCR send signals once it has bound

A

they have CD3

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13
Q

what is CD3

A

6 chains that are bound to the TCR with ITAM in the cytoplasm

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14
Q

what is ITAM

A

a part of the CD3 of TCRs
Immunoreceptor Tyrosine-based Activation Motifs
the part that signals to the cell when the TCR has bound an antigen/costimulator

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15
Q

the BCR (B-cell receptor) is immunoglobin that is membrane bound, what is the structure of the TCR (T-cell receptor)

A

2 immunoglobin domains that aren’t identical

it is an alpha-beta heterodimer with two proximal constant regions, and two variable distal regions

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16
Q

what are the three hypervariable regions of the variable region of the TCR. and what is their function

A

CDR1, CDR2, and CDR3

these contact the peptide-MHC complex

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17
Q

what are the four sources of variability to the TCR

A
  1. different V and J segments of the alpha chain
  2. different V, D, and J segments of the beta chain
  3. different combinations of the alpha and beta chains
  4. variability of the junctions between alpha and beta
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18
Q

what does positive selection of T-cells get rid of

A

those T-cells with weak binding to the Self-peptide/self-MHC complex

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19
Q

what does negative selection of T-cells get rid of

A

those T-cells with too strong of a binding to self-peptide/self-MHC complex

20
Q

the three parts of the variable region of TCRs each bind to what

A

CDCR1 binds to the MHC molecule
CDCR2 binds to both the MHC and the peptide/antigen
CDCR3 binds to the peptide/antigen

21
Q

of the three parts of the variable region of TCRs, which one is the most variable

A

CDCR3 the one that binds the peptide/antigen

22
Q

Where do the coreceptors (CD8 and CD4) on T-cells bind to the MHC/antigen complex

A

they bind to the MHC

23
Q

what does the binding of CD8 and CD4 do for the binding between the TCR and the Antigen MHC complex

A

it increases the avidity of the binding

and helps the T-cell bind to the right MHC class

24
Q

what class of MHC does the CD8 of T-cells bind to

A

Class 1

25
Q

what class of MHC does the CD4 od T-cells bind to

A

Class 2

26
Q

what does CTLA4 do, and what happens if you don’t have it

A

it doesn’t cause an increase in CD40L and there fore CD28 on the T-cell. This keeps the T-cell from expressing out of control.
in mice that didn’t have CTLA4, they died of lymphoproliferative diseases

27
Q

What are the different types of T-cells that can come from CD4 T-cells

A

Th1
Th2
TREG
TH17

28
Q

what cytokine is associated with TH1 T-cells

A

IFN-y

29
Q

what do TH1 T-cells do

A 
activate:
macrophages
NK cells
CD8 T-cells
(attacks viruses, intracellular bacteria)
30
Q

What cytokine is associated with TH2 cells

A

IL-4, IL-5, and IL-13

31
Q

what do TH2 cells do

A

activate:
eosinophils, basophils, and mast cells

(attacks worms and bloodsucking insects)

32
Q

What cytokine is associated with TH-17 T-cells

A

IL-17

33
Q

what do TH-17 cells do

A

activate neutrophils

attacks extracellular bacteria and fungi

34
Q

What cytokine is associated with TREG cells

A

IL-10, TGF-beta

35
Q

what do TREG cells do

A

activate dendritic cells

inhibits other effector T-cell types

36
Q

what do most CD8 T-cells differentiate into

A

cytotoxic T-cells

37
Q

what cytokine do cytotoxic T-cells produce, and what do they do

A

IFN-y (upregulates MHC class 1 and immunoproteasome)
TNF (can activate apoptosis in some cells)
Chemokines (attrack other immune cells)

38
Q

What are the cytotoxic mechanisms of Cytotoxic T-cells

A
  1. Perforin
  2. granzymes
  3. Fas ligand
39
Q

what causes perforin and granzymes to be secreted from Cytotoxic T-cells

A

the binding of the T-cell to the MHC/antigen complex causes a release of Ca++. this causes the release of Perforin and granzymes

40
Q

how does perforin kill cells

A

creates pores in the cell membrane, which allows the granzymes to enter

41
Q

how do granzymes kill cells

A

they enter the cell through perforins and cleave caspase 3 and Bid. these cause DNA fragmentation, and inactivates cellular repair

42
Q

the binding between cytotoxic T-cells and the target cell is transient, but what can cause it to be stronger

A

LFA-1 and ICAM interactions (these also help focus the secretory apparatus toward the target cell)

43
Q

how do cytotoxic T-cells prevent perforination of themselves that would lead to their own destruction

A

the vesicles that contain the perforin and granzymes have Cathepsin B on their membrane, and when the vesicle makes it to the cell membrane, they remain at the cell membrane and prevent the fusion of perforin to the cell

44
Q

what leads to the decrease of T-cells after an immune response to maintain homeostasis

A

they are programmed to die unless they receive survival signals (cytokines, costimulatory signals)

45
Q

what is lymphopenia

A

low lymphocyte levels in the blood

46
Q

what can cause lymphopenia

A

viral infection or age

DMD 5244 (Immunity) (16 decks)

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