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Immunology > activation of T lymphocytes > Flashcards

activation of T lymphocytes Flashcards

1
Q

naive T cells transiently ___ with many DCs and stop when they find ___ Ag for their TCR

A

interact

specific

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2
Q

The T cells are activated to differeneitate into effector cells. Then activated T cells may:

  1. remain in the lymphoid organs to help:
  2. migrate to sites of infection to help:
A
  1. B lymphocytes
  2. activate macrophages
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3
Q

phases of T cell responses:

  1. Ag recognition by T cells induces ___ secretion resulting in clonal expansion as a result of cell proliferation and differentiation of the T cells into effector or memory cells
  2. the effector CD4 T cells response to Ags by producing cytokines that have several actions, such as the recruitment and activation of leukocytes and ____ of B cells
  3. the effecotor CD8 CTLs function by ____ infected and altered host cells
A
  1. IL-2
  2. activation
  3. killing
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4
Q

generally, T cells only recognize ____ ____ ____ Ag presented via ____

A

linear protein peptide

MHC

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5
Q

naive T cells are only activated by _____

effector T cells can respond to Ag presented by ____ and ____

A

DCs

B cells and macrophages

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6
Q

the proliferation of T lymphocytes and their differentation into effector and memory cells requires 3 signals

1.

2.

3.

A
  1. Ag recognition
  2. costimulation
  3. cytokines
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7
Q

superantigens:

  1. activates ____ T cells without the presence of Ag or other stimulatory factors
  2. bind MCH II on APC variable ___ subunit of the TCR; NOT the ___ ___ ___
  3. casuses massive proliferation and production of ____ cytokines
A
  1. CD4
  2. beta subunit of the TCR; NOT the peptide binding groove
  3. proinflammatory
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8
Q

mitogen

A

peptide or small protein that induces a cell to being cell division: mitosis

e.x. - superantigen

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9
Q

proliferation and differentation of T cells - Signal 1 (Ag recognition):

  1. TCR recognizing and binds to MHC complex on ____
  2. CD4/CD8 complex containing ____ phosphorylate ____ on ____ chains
  3. ____ binds to p-ITAMs and LCK activates ZAP-70 via phosphorylation
  4. ZAP-70 phosphorylates ____ and ____ which act as scaffolding for proteins
  5. actives the MAPK, RAS, and PLC-gamma pathway

(not a strong enough stimulation)

A
  1. DCs
  2. LCK ITAMs zeta
  3. ZAP-70
  4. LAT and SLP-76
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10
Q

proliferation and differenation of T cells - Signal 2 - Costimulation:

  1. ____ on naive cells wil bind to the ____ on the DC
  2. activation of the pathways that lead to ____ , ____ , cyclins, and differentiation factors
  3. upregulation of ____ and other CD28-like receptors (these are inhibitory receptors that will compete for binding with the CD80/86) to regulate the immune response

(unactivated DCs express low levels of these costimulatory molecules, while activated DCs express high levels)

A
  1. CD28 CD80/86 (B7)
  2. survival factors (Bcl-2) , proliferation factors (IL-2)
  3. CTLA-4
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11
Q

microbes and cytokines produced during innate immune responses (inflammation) activate DCs to express ____ , such as CD80/86 molecules

A

costimulators

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12
Q

activated DCs produce cytokines such as ____ which stimulate the ____ of naive T cells into effector cells

A

IL-12

differentiation

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13
Q

TCR-signaling alone produces a strong activation of ____ but only weak activation of ____ and ____

A

NFAT

NF-kB and AP-1

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14
Q

costimulation induces ____ and ____

A

NFkB and AP-1

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15
Q

the expression of ____ co stimulators is regulated and ensures that T lymphocyte responses are initiated only when needed

A

B7 (CD80/86)

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16
Q

CTLA-4 will bind to ____ on activated cells to prevent the further overativation of T cells

A

CD80/86 (B7)

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17
Q

CTLA-4 is not expressed on the surface of

A

naive and memory cells

(is stored in intracellular vesicles

18
Q

major function of PD-1 is

A

the programmed cell death of T cells following inflammaotry immune responses

19
Q

the stronger the stimulation through the TCR (and CD28) the ____ the amount of CTLA-4 that is dposited on the T cell surface

A

greater

20
Q

PD-1 downregulates the activity of T cells and thus limits ____ ____ damage in response to a microorganism infection in that tissue

A

collateral tissue

21
Q

PD-1 is upregulated by

A

IFN-gamma

22
Q

excessive induction of PD-1 on T cells can induce an ____ state in T cells

A

anergic

23
Q

proliferation and differentation of T cells - Signal 3 (cytokines-differentiation):

cytokines in the environment will determine what effector T cell is produced

  1. IL-12 → ____ → ____ → ____
  2. IL-4 → ____ → ____ → ____
  3. IL-6 → ____ → ____ → ____
  4. TFG-beta → ____ → ____ → ____
A
  1. IL-12 → STAT4 → T-bet → Th1 cell
  2. IL-4 → STAT6 → GATA3 → Th2
  3. IL-6 → STAT3 → RORgammat → Th17
  4. TFG-beta → SMAD2-SMAD4 → FOXP3 → Treg
24
Q

changes in protein expression:

  1. recognition of the ____ to its antigen
  2. upreguation of the ____ transcription product
  3. ____ production and release
  4. ____ expression (reduces surface expression of S1PR1)
  5. ____ expression
  6. ____ expression
  7. cell division (growth and ____)
A
  1. TCR
  2. c-Fos
  3. IL-2
  4. CD69 (retention in lymph nodes)
  5. IL-2Ralpha (proliferation)(increases affinity of IL-2 receptors)
  6. CD40L (activation of DCs, macrophages, T/B cells)
  7. proliferation
25
Q

IL-2 stimulates the ____ , ____ , ____ of Ag-activated T cells

A

survival, proliferation, and differentiation

26
Q

characteristics of IL-2:

  1. IL-2 induces the anti-apoptotic protein ____
  2. stimulates cell cycle progression by degrdation of the cell cyle inhibitor ____
  3. is required for the survival and function of ____ cells
A
  1. Bcl-2
  2. p27
  3. Treg
27
Q

decline and resolution of the T cell response:

  1. elimination of Ag leads to ____ of the T cell response
  2. this leads to decrease in ____ produced
  3. lack of IL-2 leads to decrease in ____ which leads to intrinsic apoptosis
  4. inhibitory receptors ____ and ____ lead to cell death
  5. ____ cells can regulate the survival of the remaining T cells
A
  1. contraction
  2. IL-2
  3. Bcl-2
  4. CTLA-4 and PD-1
  5. Treg
28
Q

linear model of T cell differentiation

A

T cells differentiate → most effector cells die → a few survive and become memory cells

(most accepted)

29
Q

branched theory of memory T cell differentiation

A

effector and memory cells are alternative fates of activated T cells (T cells differentiate into either memory cells or effector cells)

30
Q

____ TF promotes the generation of memory cells

A

Blimp-1

31
Q

memory T cells constitute the most ____ lymphocyte population in the body during the lifetime

A

abundant

32
Q

the vast majority of memory T cells reside in ____ site

A

tissue (including lymphoid tissue, intestine, lungs, and skin)

33
Q

the ____ TF drives differentation of effector cells in CD4 T cells

A

T-bet

34
Q

resident memory T cells (TRM)

  1. produce ____ and ____
  2. are specific for pathogens and other Ags that have been encountered previously through that ____ epithelium
  3. remain at ____ sites
A
  1. IFN-gamma and TNF
  2. barrier
  3. tissue
35
Q

central memory T cells (TCM):

  1. express ____ and ____
  2. home mainly to ____ , ____ and circulate in the blood
A
  1. CCR7 and L-selectin
  2. LNs, spleen
36
Q

effector memory T cells (TEM) :

  1. do not ____ but produce IFN-gamma and TNF or become ____
  2. upon entering the tissue can become ____ cells and reside in epithelial barrier tissues at the interface between the host and the environment
  3. circulate in ____
A
  1. proliferate cytotoxic
  2. TRM
  3. blood
37
Q

properties of memory cells:

  1. can survive in a quiescent state without ____
  2. respond to repeated exposure ____ and with a great response (naive T cells: 5-7 days ; memory T cells: 1-3 days)
  3. the number of memory T cells specific for any Ag is ____ than the number of niave T cells specific for the same Ag
  4. undergo slow ____ process leading to longer life span
  5. maintenance requires ____ but not antigens
  6. environmental ____ and ____ cytokines induce the expression of anti-apoptotic proteins and stimulate low-level proliferation
A
  1. Ag
  2. faster
  3. greater
  4. self-renewing
  5. cytokines
  6. IL-7 and IL-15
38
Q

markers of memory T cells

A

IL-7R, CD45, and CD27

39
Q

functional naive T cell output decreases after puberty due to thymic ____ , resulting in increased homeostatic proliferation of existing naive T cells and eventually phenotypic conversion of naive T cells into virtual memory cells

A

involution

40
Q

in contrast to the shrinking naive compartment and its impaired ability to activate and differenetiate with age, the proportion of memory T cells increases during early life, remains stable throughout adulthood, but starts to show senescent changes after about ____ years

A

65

41
Q

one of the most prominent T cell changes to occur with age is the loss of ____ expression and the progressive accumulation of hightly differentiated CD28- TEM cells, mainly in the CD8 T cell population

A

CD28

Immunology (23 decks)

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