T cellls: Intro/overview/signal 3

Question 1

Describe big picture image

Answer 1

Signal 3 happens in lymph node
T and B cell activation
Cell mediate immunity = back to site of infection
Regulation = downreg and memory

Question 2

Activation of cd4 and cd8 T cells

Answer 2

Signal 1 - pmhc:tcr
Signal 2 - b7:cd28
Signal 3 - cytokines

Question 3

What do effector functions depend on

Answer 3

Subset T cells - cd8 or cd4

Question 4

Describe cd4 effector functions

Answer 4

Activation of macrophages, B cells and other cels

Question 5

Describe cd8 effector functions

Answer 5

Killing of infected target cells, macrophage activation

Question 6

Describe activation of B cells

Answer 6

Via Tfh - follicular helper cells
Signal 1 - p:bcr
Signal 2- th2 cytokines
Linked recognition

Question 7

Name some diff roles of diff effector T cells

Answer 7

Some help activate B cells
Some help activate macrophages - especially ones with infection persisting in macrophage
Some kill infected cells directly

Question 8

What do effector T cells do

Answer 8

Leave lymph node
Efferent lymphatic vessels —>thoracic duct —> blood stream

Question 9

Describe cell mediated immunity

Answer 9

Th1 cytokines promote tc killing and macrophage ros killing

Question 10

What is signal 3

Answer 10

Differentiation
Cytokines directing T cell differentiation into distinct effector cell types

Question 11

What do the 3 signals result in

Answer 11

Intracellular signalling Leading to change
Activation, proliferation, survival, differentiation

Question 12

What is lymphocyte activation

Answer 12

= proliferation + differentiation

Question 13

Describe what activated T cells do

Answer 13

Proliferate in response to il2
Differentiate

Question 14

What can T cells differentiate into

Answer 14

Cd4+ t helper cells - th0 to th1, th2, tfh or th17 or others
Cd8+ T cells = cytotoxic t lymphocyte - ctl
Regulatory T cells

Question 15

Describe regulatory T cells

Answer 15

Some th0 cells can differentiate to t reg but also some naive T cells are already t reg

Question 16

What is naive T cell

Answer 16

Th0

Question 17

What do effector T cells result from

Answer 17

Must have gotten all 3 signals
Effector T cells are resulting from differentiated T cells from activated T cells

Question 18

How can effector T cells be classified

Answer 18

Tf they express
Profile of cytokines they make
Main function in adaptive immunity

Question 19

What do naive cd8+ T cells differentiate into

Answer 19

Cytotoxic t lymphocytes
Only one option

Question 20

Describe effector T cells once activated

Answer 20

Does not require co stimulation to act - only interacts with tcr bc need to be specific.
Recognition —> proliferation/differentiation —> effector function
HAS TO ONLY RECOGNIZE p:Mhc1 to see if specific to this cell

Question 21

What determines the fate of T cells

Answer 21

Cytokines

Question 22

Name 5 subsets of cd4 T cells

Answer 22

Th1
Th2
Th17
Tfh
Treg

Question 23

Describe what effector T cells secrete

Answer 23

Diff cytokines secreted by effector cytokines have diff functions
Effector T cells = impact functionality of other immune cells
Clear diff microorganisms
Cd4 T cells help clear infections in many ways

Question 24

What does pathogen do

Answer 24

Depends on pathogen
Pathogen —> polarizing cytokine —> diff effector functions

Question 25

What regulates differentiation of t helper cells

Answer 25

Regulated by signal 3 cytokines = called polarizing cytokines - responsible for guiding T cell towards one of several diff effector fates

Question 26

Describe apcs binding to pampas

Answer 26

Apcs bind pamps via prrs = induce cytokine secretion Diff prrs engaged via diff pamps = diff cytokines produced

Question 27

What induced th 2 subset

Answer 27

Worms/helminth stimulate il-4 polarizing cytokines to induce th2 subset

Question 28

What induces th1 subset

Answer 28

Viruses stimulate il-12 polarizing cytokine to induce th1 subset

Question 29

Name steps to make effector T cell

Answer 29

Pamps from pathogens bind prrs —> polarizing cytokines —> stats —> master gene regulators —> effector cytokines

Question 30

Describe polarizing cytokines

Answer 30

Fate specifying cytokines Impact differentiation of T cells - signal 3

Question 31

What are produced by differentiate T cells

Answer 31

Effector cytokines

Question 32

How does signal 3 exert its effect - cytokines

Answer 32

Cytokines bind their receptor and induce intraclelualr signalling Occurs through stat proteins —> once phosphorylated = act as Tfs - go inside nucleus and bind promoters

Question 33

How does signal 3 exert its effect - genes

Answer 33

Key gene transcribed is another tf = master transcription regulator = go into nucleus and bind promoter regions fo genes that encode specific effector cytokines that subset T cells will produce

Question 34

How does signal 3 exert its effect - new tf

Answer 34

New tf can then bind response element on promoter regions of genes coding for specific effector cytokines—> determine activity of activated differentiated T cell subset

Question 35

Signal 3 summary

Answer 35

Signal 3= polarizing cytokines Tf = phosphorylation of stats, diff stat proteins activated, Then master transcriptional regulator = depends on type of stat phosphorylated Dictates effector cytokines

Question 36

Describe type 1 response gen

Answer 36

Virus Il12 = polarizing cytokine Stat4 and stat1 = phosphorylated T bet = master transcriptional regulator - after express = then considered effector cell —> th1 —>secreted ifn-gamma effector cytokine

Question 37

Describe type 2 response gen

Answer 37

worm Il4= polarizing cytokine (from dc and neighbouring cells) Stat6 = phosphorylated Gata3 = master transcriptional regulator - after express = then considered effector cell —> th2 —>secretes il4,5,13 effector cytokines

Question 38

What happens after clearance of infection

Answer 38

Downreg T cell activity and immunological memory

Question 39

Name the 3 main steps of T cell differentiation

Answer 39

Tcr signalling Costimulattory interaction Cytokines signalling = autocrine il2 and paracrine il12

Question 40

Polarizing cytokine secreted by what

Answer 40

Apc - dendritic cell By neighbouring innate and adaptive immune cells