Exam 2 - Chapter 6, how T cells work

what two jobs do helper t cells have

1. remain in blood and lymph to help B and CTLs

2. leave blood and enter battle sites

how do helper t cells "help" b cells and CTLs

they omit cytokines

what is the importance of cytokines

they drive the immune response

give the address for anatomical location and pathogen identity

what cells provide helper t cells with "education" to tell them what type of invader and the location of the invader

dendritic

how do dendritic cells identify a pathogen in order to inform the helper t cells

TLR on dendritic cell recognizes PAMP on invader

how do dendritic cells provide the helper t cells with the pathogen's regional identity

they recognize the cytokines being omitted

what two factors influence which fate a helper t cell will fall into

1. cytokines released by APDC

2. strength of MHC II-peptide interaction

what defense are TH1 cells used for

viral or bacterial attack inside cells (intracellular pathogen)

what are the effector cytokines of a TH1 (the cytokines omitted by Th1)

TNF, IFN-gamma, IL-2

what cytokine does and APDC release at the time of activation in order for a TH1 bias to occur

IL-12

what is the role of TNF

activate macrophages and natural killer cells

what is role of IFN-gamma

activate macrophages and keep them active

what antibodies do IFN-gamma cytokines tell B cells to make

IgG

what does IL-2 do

proliferation of CTLs, NK cells, and more Th1

recharge NK cells

what defense are Th2 used for

parasitic/helminths attack or food contaminated with pathogenic bacteria (GI system)

what cytokine does APDC omit to produce a Th2 bias

none, IL-4 comes from the GI system and has this role

what are the effector cytokines for a Th2 bias (the ones omitted by the Th2 celll)

IL-4, IL-5, IL-13

what is role of IL-4

growth factor to proliferate T cells and B cells making IgE

IL-5 acts on B cells to tell them to produce what antibody? where?

IgA, peyers patches

what does IL-13 stimulate

mucus in intestine

do Th11 or Th2 cells receive a stronger stimulus before undergoing differentiation

th1

is IgA anti- or pro-inflammatory

anti

low affinity IgA antibodies are important to confine what to the intestinal lumen

commensal bacteria

in the case of a bacteria replicating in a macrophage, such as Mycobacterium Leprae, would you want a th1 bias or th2 bias? why?

th1

keeps macrophage activated from IFN-gamma so they can present antigen

What defense are Th17 cells used for

fungal attack and bacteria in mucosal barriers (extracellular)

what cytokines are released by APDC to produce a Th17 bias

TGF-beta, IL-6, IL-23

what are the effector cytokines of a th17 cell

IL-17

IL-21

IL-23

what cells does IL-17 recruit in large numbers

neutrophils

what does IL-21 promote growth of

more th17 cells

what are the non-committed t cells that change based on the cytokine environment

Th0

what are Tfh helper t cells

follicular helper t

what pathogens do Tfh defend against? what is the immune reaction of these cells?

extracellular pathogens

antibody production

what do Tfh cells require for activation

1. APDC activate T cell (B7/CD28)

2. Activated B cell has ICOS-L which binds with ICOS on the activated T cell causing the T cell to differentiate into a Tfh

where do Tfh cells travel to in a lymph node, what occurs here?

germinal center, activates naive b cells to allow class switching and somatic hypermutation

what cytokine do follicular helper t cells release

IL-21

what are the target cells of each bias respectively

th1

th2

th17

tfh

macrophage

eosinophil

neutrophil

b cells

Th9 cell produces what cytokine? what is it used to defend against?

IL-9

worms

Th22 cell produces what cytokine? what is it used to defend against?

IL-22

skin

t/f

cytokines have a very limited range and only have a local impact

true

what is cross regulation

helper t cells omit cytokines which inhibit other biases

Th1 makes IFN gamma which inhibits production of what bias

th2

iTreg/pTreg makes IL-10 which inhibits production of what bias

th1

what do superantigens (sag) do

- attack to MHC II and TCR to bypass need for TCR to recognize an antigen

- forces t cell into activation

- could be against self or foreign

- increase cytokine release

what is an example of an exogenous superantigen exotoxin that is caused by our own immune response against ourselves

toxic shock syndrome toxin

what does a naive CTL need for activation

activated dendritic cell

when an activated dendritic cell and Th cell bind, they emit cytokines which attract what cells

CTLs

once the CTL is activated, it leaves the lymph organ and enters the tissue to be ____ by a macrophage. The CTL can then scan any call it finds

reactivated

how do CTLs kill

- deliver package with perforin and granzyme B

- Fas Ligand on CTL bind to Fas Protein on target = apoptosis

what is known as the death receptor and is found on target cells

fas protein