Lecture 9: Activation of T Lymphocytes Flashcards Preview

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Flashcards in Lecture 9: Activation of T Lymphocytes Deck (28):
1

The proliferation of T lympohcytes and their differentiation into effector and memory cells reuires what three signals

  • Ag recognition (signal 1)
  • Costimulation (signal 2)
  • Cytokines (signal 3)

2

Activation of naive T cells requires recognition of Ag presented by ____ meanwhile effector T cells can recognize Ags presented by ____ and _____

Naive T cells require DCs

Effector T cells can recognize Ags presented by Tissue macrophages and B cells 

3

Superantigens (Sags) bind simultaneously 

  • MHC class II molecules (not in the peptide-binding groove) and the V region of the beta subunit of the TCR 
  • this leads to T cells produce massive amounts of cytokines (such as TNF-alpha, IL-1beta, and IL-2) which may lead to shock 

4

The best characterized costimulatory pathway in T cell acitvation 

  • T cell surface receptor CD28
  • binds costimulatory molecules B7-1 (CD80) and B7-2 (CD86) expressed on activated APCs
  • B7 costimulators are regulated and ensure that T lympocyte responses are initiated only when needed. 

5

CTLA-4-mediated immune checkpoint is induced in naive T cells at the time 

of their intial response to Ag

6

The stronger the stimulation through the TCR and CD28 the greater the amount of ___ that is deposited on the T cell surface from the inracellular vesicles 

CTLA4

7

Inflammatory signals in the tissues have what effect on expression of PD1 ligands 

  • induce expression of PD1
  • this is a way to downregulate the activity of T cells and thus limit collateral tissue damage in response to a microorganism infection in that tissue. 

 

8

9

10

11

12

No other cytokine can replace ____ for the mainenance of functional Treg cells 

IL-2

13

CD69 binds to and reduces surface expression fo the ________ receptor _____

  • Sphingosine-1-phosphate receptor S1PR1
  • as a result, activated T cells are retained in the LNs long enough to receive the signals that initiate their proliferation and differentiation into effector and memory cells 

14

IL-2Ralpha is also known as CD___

CD25

15

What are the inhibitory receptors on T cells

  • CTLA4
  • PD-1

16

various regulatory mechanisms contribute to the normal contraction of T cells, such as:

  • The inhibitory receptors CTLA4 and PD-1
  • Apoptosis induced by death receptors TNFRI and Fas
  • Treg cells
  • (not that IL-2 secretion decreases as well) 

17

The vast majority of memory T cells reside in 

tissue sites, including lymphoid tissues, intestines, lungs and skin 

18

What transcription factor promotes the generation of T memory cells 

Blimp-1

19

The number of memory T cells specific for any Ag is ____ than the number of naive cells specific for the same Ag

greater (typically 10-100 fold more than the pool of naive cells) 

20

What cytokines induce the expression of anti-apototic proteins and stimulate low-level proliferation of memory cells 

IL-7 and IL-15

21

memory T cells pass through what three distinct phases

  • Memory generation
  • memory homeostasis
  • immunosenescence

22

What are the phenotypic markers for memory T cells 

  • IL-7R
  • CD45
  • CD27

23

The central memory T cells (Tcmcells) express the chemokine receptor ____ and _____ and home mainly to 

  • The central memory T cells (Tcmcells) express the chemokine receptor CCR7 and L-selectin and home mainly to LNs, spleen, and circulate in the blood
    • Proliferate (high production of IL-2) and generate many effector cells on Ag challenge

 

24

Effector memory T cells (TEMcells) circulate in the blood. They do not proliferate but produce

  • IFN-gamma and TNF or become cytotoxic

25

Resident tissue memory T cells (TRMcells) reside in epithelial barrier tissues at the interface between the host and environment. They produce

IFN-gamma and TNF and are specific for pathogens and other Ags that have been encountered previously though that barrier epithelium 

26

27

CD69 binds to and reduces surface expression of the 

  • sphingosin 1-phosphate receptor (S1PR1)
    • As a result, activated T cells are retained in the LNs long enough to receive the signals that initiate their proliferation and differentiation into effector and memory cells

28

Expression of CD40L (CD154) is highly increased in activated T cells within ___ to ___ hours after Ag recognition

  • 24-48 hours