notecards Flashcards
what is another name for a killer T cell
Cytotoxic T cell
what activates killer T cells
MHC 1 on cells
what activates helper T cells
MHC 2 on APC
what does a regulatory T cell do
prevent the immune system from overreacting (inhibition)
what does the helper T cell need help from to become activated
an APC
what are the APC’s
activated dendritic cell, activated macrophage, or activated B cell
for activation of a T cell what must happen with the TCR
must recognize it cognate antigen
what must the co-receptor recognize in order to allow activation of T cells
MHC (I or II)
if the T cells see “self being presented by other cells it will _____
Die
if the T cells recognizes self antigen, but doesnt get co-stimulation it will be ____
rendered inactive (anergized) and eventually die
if the T cells see non-self and gets co-stimulated the t cell will _____
be activated
if TCR recognized MHC plus self peptides it will
commit suicide (apoptosis)
if TCR recognizes cognate antigen on MHC with no co-stimulation it will
T cell will be anergized (inactivated)
if TCR recognizes cognate antigen on MHC plus co-stimulation it will
be activated
T cells only recognize _____ presented by MHC I or MHC II molecules
peptides
are all TCR on mature T cells identical
YES
what is the name given to the group of signaling proteins of a T cell
CD3
where are non traditional T cells most abundant
intestine, uterus and tongue
are tradition or non traditional TCR’s more diverse
traditional
what is needed for T cell recognition
TCR(alpha, beta) and co-receptor (CD4 or CD8)
what is needed for T cell co-stimulation
B7 on APC and CD28 on T cell
what is needed for T cell signaling
CD3 and CD28 on T cell
where is CD4 usually expressed
on helper T cells
what does CD4 attach
TCR ro MHCII molecules
what does a CD4 signal
help
what does a CD8 signal
KILL
where is CD8 usually expressed
on killer T cells (CTLs)
what does the CD8 attach
TCR to MHC I molecules
which-receptors are expressed by T cells in the thymus
both
which MHC are peptides being made in the cell
MHC I
which MHC are peptides eaten by APC
MHC II
what is the co-stimulatory molecule expressed on the surface of APC
B7
what is a receptor molecule on the T cell, when activated it amplifies the signal and lowers the number of TCR corsslinks needed for activation
CD28
why is co stimulation required
the connection between the receptor and the nucleus of naive T cells is weak and a co-stimulator creates a better connection
does a naive T cell have many or few lipid rafts
FEW
does an experienced T cell many or few lipid rafts
MANY
why do experienced T cells not need co-stimulation for reactivation
because the maintain the lipid rafts
what re-activates a T cell at the battle site
macrophages
what initially activates T cells before they leave for the battle site
dendritic cells
if a helper T cell finds its cognate antigen what co receptor attatches it to the dendritic cell
the CD4 co-receptor on the T helper cell attaches to the MHC II on the dendritic cell
if a helper T cell finds its cognate antigen what proteins attach the Th cell and dendritic cell
DC40L on the Th cell attaches to the CD40 on the dendritic cell
how long does complete activation of a helper T cell take
4-10 hours
what happens to the dendritic cell (APC) when it parts from the T helper cell after activation
it goes on to activate other helper T cells
after the helper T cell and the dendritic cell part after activation what does the helper T cell do and what is needed for this to happen
the helper T cell will proliferate and make more IL-2 in order to continue to proliferate (positive feedback)
what are the TWO jobs of a helper T cell
remain in blood and lymph providing help for B cells and CTL’s and leave the blood and enter battle sites providing help for soldiers on the front line
what help does the helper T cell bring to the battle
Cytokines
what are cytokines
communication proteins for the immune system and others
what are the three major subsets of cytokines
TH1 TH2 TH17
what does a TH1 helper T cell respond to
viral or bacterial attack
what cytokines are in the TH1 subset
TNF, IFN-y, IL-2
what does IFN-y do
keeps the marophages active, and tells B cells to make IgG3
what does IL-2 do
recharges natural killer cells, and stimulates proliferation of CTLs, NK cells and TH1cells
what is TH@ helper t cells respond to
parasitic attach of food contaminated with pathogenic bacteria (intestines under attack)
what are the cytokines released in the TH2 subset
IL-4, IL-5, IL-13
what does IL-4 do
growth factor to proliferate T cells (releasing TH2 cytokines) and for B cells that make IgE
what does IL-5 do
causes B cells to make IgA
what is IgA
and antibacterial in the intestines
what does IL-13 do
simulates mucus in the intestine
what does th17 defend against
fungal attack
what cytokines are in the th17 subset
IL-17 and IL-21
what causes the TH17 subset to be released
dendritic cells make TGFß
what does IL-17 do
recruits massive numbers of neutrophils to the area
what does IL-21 do
causes growth of more TH17
what causes a th0 to become th1
IL-12 from macrophage
what causes th0 to become th2
IL-4 from an unknown source
what causes th0 to become th17
IL-6 and TGFß from AP dendritic cell
can a helper T cell switch what kind of cytokines it is producing after it begins
no it is committed to one subset once it startes
what kind of range do cytokines have
very limited (local impact only)
what is the benefit to having a limited range on cytokines
it allows the body to defend against multiple types of invaders in different body locations simultaneously
what does a naive CTL need to be activated
only an activated dendritic cell presenting the cognate antigen on a MHC I
what happens when dendritic cells and helper T cells bind
they emit cytokines attracting CTLs
what happens when a activated dendritic cell, CTL and helper T cell get together
the response is much greater
what does the helper T cell supply to regulate the size of the CTL response and what does it cause
IL-2 is supplied causing CTL proliferation regulating the size of response
how does a CTL kill by delivering “gifts”
uses perforin to poke holes in a membrane then releases granzyme B initiating a chain of reactions leading to target cell sicide
what can the CTL connect in order to kill some cells
a CTL can connect its Fas ligand to the fas protein on a target cell signaling the cell to commit suicide
what is necrosis of a cell
means enzymes and chemicals from the dying cell are released into surrounding tissue causing extreme damage
what is apoptosis
the enzymes and chemicals from the dying cell are neatly contained in vesicles, the vesicles are eaten and disposed of by macrophages
