BIOL 435 Ch. 10 p.2 (T-cell Activation and more) Flashcards

1
Q

5 distinct subsets of helper T-cells

A
  • TH1
  • TH2
  • TH17
  • Treg
  • TFH
  • each produce a distinct cytokine profile and regulates distinct activities within the body
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2
Q

TH1

A

-regulate immunity of intracellular bacteria and viruses

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3
Q

TH2

A

-regulate immunity to worms

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4
Q

TH17

A

-regulate immunity to extracellular bacteria and fungi

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5
Q

Treg

A
  • inhibitory in terminating immune responses and inhibiting autoimmunity
  • suppress immune response
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6
Q

TFH

A
  • follicular helper
  • regulate humoral immunity (B-cells)
  • regulates affinity maturation of germinal centre B-cells
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7
Q

polarizing cytokines for TH17

A
  • TGF-beta
  • IL-6
  • IL-23
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8
Q

effector cytokines from TH17

A
  • IL-17A
  • IL-17F
  • IL-22
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9
Q

effector functions TH17

A

-combats extracellular pathogens in barrier tissues
>autoimmunity
>tissue inflammation

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10
Q

polarizing cytokines for TH2

A

-IL-4

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11
Q

effector cytokines from TH2

A
  • IL-4
  • IL-5
  • IL-13
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12
Q

effector functions TH2

A
  • combats infection
  • activates eosinphils
  • involved in allergies
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13
Q

polarizing cytokines for TH1

A
  • IL-12
  • IFN-gamma
  • IL-18
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14
Q

effector cytokines from TH1

A
  • IFN-gamma

- TNF

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15
Q

effector functions TH1

A
  • combats intracellular pathogens
  • activates macrophages
  • tissue inflammation
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16
Q

Type 1 response

A

-intracellular pathogens inducing cell-mediated immunity

>most viruses, some bacteria and fungi

17
Q

Type 2 reponses

A
  • pathogens inducing humoral immunity

- particullarly extracellular parasites (ex. worms)

18
Q

cytokines can achieve TH1/TH2 helper subset cross-regulation

A
  • IFN-gamma
  • IL-4
  • IL-10
19
Q

IFN-gamma

A
-from TH1 responses inhibit IgG1/IgE class switching
>a common TH2 induced response
20
Q

IL-4

A

-from TH2 responses inhibits production of IgG2alpha

>a common TH1-induced response

21
Q

IL-10

A

-from TH2 responses inhibit TH1 responses by suppressing the production of inflammatory mediators from APCs

22
Q

master regulators

A
  • commit T-cells to one subset or the other
  • T-Beta
  • GATA-3
23
Q

T-Bet

A

-suppressess TH2 pathway gene expression

24
Q

GATA3

A

-suppresses TH1 pathway gene expression

25
TFH cells provide
- wide range of help to B-cells - required for germinal centre formation - provide signals that drive affinity maturation - enhance B-cell class switching
26
helper T-cells commitment to a lineage
- early in differentiation TH subpopulations may be able to shift - fluidity makes definitive establishment of helper cell lineages difficult
27
genetic differences in subset differentiation potential
``` -may lead to different outcomes >leprosy >HIV >reduced TH1 responses >TH17 for controlling infections ```
28
tuberculoid leprosy
-stimulates TH1 responses with high levels of IL-2, IFN-gamma and LT-alpha
29
lepromatous leprosy
-stimulates TH2 responses with high levels of IL-4, IL-5 and IL-10 from other subsets inducing Treg cells >not as effective at clearing disease
30
reduced TH1 response
- due to virally produced IL-10 homolog in EBV infections | - confers a survival advantage
31
HIV progression
- to AIDS | - possibly influenced by a shift from TH1 to TH2 responses over time
32
differences in surface protein expression
- between naive, effector and memory T-cells | - subsets differentiated by expression of certain cell surface markers
33
T-cell memory types
- TCM - TEM - TRM * distinguished by locale and commitment to effector function
34
TCM cells
- central memory T-cells - reside in/travel between secondary lymphoid tissues - live longer/divide more times than TEM cells - rapidly reactivated by second Ag exposure - can differentiate into several subsets depending on cytokine environment
35
TEM cells
- effector memory T-cells - travel to/between tertiary tissues - contribute better to first-line defenses - shift right back into effector functions on second Ag exposure
36
TRM cells
- permanent residents of perviously infected tissue - respond upon reinfection - CD8+ TRM found in multiple tissues
37
when do memory cells arise?
- early in immune response (3 days) - TCM before TEM - TEM derived from fully differentiated effector cells - arise from assymetrical division of activated T-cells - self-renewing memory SC populations may be generated during T-cell activation
38
CD4+ vs CD8+ memory T-cells
-more CD8 than CD4 >proliferate more during their responses >due to differences in life span (CD4) are shorter lived
39
memory cells maintained for years?
- seems to depend on cytokine input to induce occasional cell divisions - IL-17 and IL-15 appear important to homeostatic proliferation