in order for the cell-mediated response to be active, what must always be present?
can humoral immunity be transfered to a fetus?
can cell-mediated immunity be transfered to a fetus?
what will IL-2 do?
activate: B, NK, T helper, T cytotoxic cells
T helper cells help defend against?
parasites, cancer, bacteria/viruses inside host cell
T helper cells will regulate the proliferation and activity of these cells:
B cells, macrophages, neutrophils
t cells only react to antigen combined or associated with this molecules
how to t helper cells kill microbes?
they stimulate macrophages that have ingested the microbe to kill it
do natural killer cells require antigen stimulation?
are natural killer cells phagocytic?
how are macrophages activated in the cell-mediated response?
by using the CD40-CD40L interaction and through INF-y
what are the 2 phases of the cell-mediated response?
1) induction phase2) effector phase
what characterises the induction phase?
CD4+ and CD8+ T cells recognise antigen presented by dendritic cells in peripheral organs causing them to proliferate and differentiate into effector cells that enter the circulation...they bind to activated endothelial cells
what characterises the effector phase?
the effector t cells will recognise the antigen and release cytokines to activate phagocytes to kill the microbe or if CTL's kill it directly
what cells will migrate through the endothelium that has been previously activated by cytokines? what cells cannot migrate through activated endothelium?
effector t cells and memory t cellsnaive t cells cant
what cells are activated and retained in the sites of infection?
t cells that specifically recognize antigen
cells that do not recognize antigen in site of infection will...
return to circulation
can resting APC's that encounter antigen stimulate T cells?can they present antigen?
nope, they don't express co-stimulators, yes they can present antigen though
what happens if t cells are exposed to antigen without co-stimulation?
they may become unresponsive to future presentations of that antigenTHEY MAY BECOME ANERGIC
what receptor do naive T cells have in order to recognize B7 co-stimulators on APC's?
when APC presents antigen through MHC to Helper T cell, what does the T helper cell do?
T helper cell will secrete IL-12 and recognize the IL-12 causing it to proliferate
when the T helper cell recognizes IL-12 and proliferates, what will some of the clones become?
some are memory and others effector cells
what cells express the low affinity IL-2 receptor complex?
Naive T cells
what will activate the IL_2 receptor complex in naive T cells? what will activation of the IL-2 receptor complex in Naive T cells cause?
antigen recognition and co-stimulationit will cause expression of IL-2 cytokine
Once naive T cells express IL-2 cytokine, what happens to the IL-2 receptor complex?
it will become high affinity
how many TCR need to be cross-linked in order for a immune response to take place?
2 or more TCR
cells use this adhesion molecule receptor to bind to endothelial cells
LFA-1 will bind to what on endothelial cells?
what is an ITAM?
tyrosine activating motif
what is used to bind to VCAM?
what are two examples of integrins?
VLA-4 and LFA-1
what receptor will bind to B7 in order to inhibit T cells?
what is CD152?
CTLA-4 will bind to naive t cells or activated t cells?
to activated t cells in order to inhibit them
when can we use CTLA-4?
when we have autoreactive T cells that are proliferating uncontrollably
When is CTLA-4 very, very, very important?
for maintaining self-tolerance
T helper cells that have differentiated express what? and secrete what?
CD40-L and secrete cytokines
T helper cells expressing CD40L will bind to what?
to macrophages with CD40 or B cells with CD40
When T helper cells bind to macrophages using CD40L-CD40, what will this do? is this a cell-mediated reaction?
it delivers the signal to kill microbes, and yes it is a cell-mediated reaction
how does effector T helper cell work in humoral immunity?
T helper cells bind to B cells using CD40L-CD40 and cause them to secrete specific antibody
What do T helper 1 cells do to phagocytes? and how do they do it?
they activate phagocytes by secretion of IFN-y
what do T helper 1 cells do to CTL's?
help them differentiate into effector CTL's
What do T helper 1 cells do to B cells?
make stimulate them to produce IgG
which subset of IgG will T helper 1 cells stimulate B cells to produce?
IgG 1 and IgG 3
what will T helper 2 cells cause B cells to do?
they will make B cells produce antibodies and class switch to IgG 4 or IgE
What do CTL's release from their granules?
perforins and gramzymes
what do perforins and gramzymes do?
cause the activation of apoptotic pathways
what accessory molecules are needed on the CTL and the target cell in order for the CTL to do its work?
LFA-1 and CD8
What ligand is expressed on CTL's surface that leads to apoptosis of the target cell?
What disease results from a mutation in the FAS-L receptor?
What type of infection in macrophages will lead to the differentiation of T helper 1 cells?
intracellular bacteria or virus
what other pathway leads to differentiation of T helper cells to T helper 1 cells?
infection of macrophages in innate immunity through engagement of toll-like receptors will lead to expression of what cytokine? though what cell-cell interaction and receptor engagement will the cytokine be released?
- T helper cell and APC engage CD40-CD40L
what does IL-12 activate in T helper cells?
what does INF-y cause in APC's?
production of more IL-12
what does INF-y activate in T helper cells?
what does Tbet in T helper cells do?
regulates differentiation to T helper 1
What does STAT 4 in T helper cells do?
causes T helper cells to differentiate to T Helper 1 cells
On what do T helper cells depend on to differentiate to T helper 2 cells?
what will IL-4 activate in T Helper cells?
In presence of antigen and while STAT 6 is activated, what transcription factor activates in T helper cells? what does it do?
GATA 3 activates and leads to T Helper 2 differentiation
what does TH1 cells secrete?
what do T helper 2 cells secrete?
TH 2 cells will recruit what cells mainly?
TH 1 cells will recruit what type of cells mainly?
TH 1 cells will stimulate what isotype subset of antibodies?
IgG 1 and IgG3
TH 2 cells will stimulate what antibody isotype mainly?
what T helper cell subset will activate macrophages to repair tissue?
IL-2 secreted by TH 1 cells will increase what molecules on macrophages and dendritic cells?
it will increase MHC 2 and co-stimulators
IFN-y secreted by TH 1 cells will help what 2 cells? how?
1) it helps macrophages by activating them (will kill microbes)
2) helps B cells to secrete IgG(1 and 3) antibodies that coat microbe for opsonization
TH 1 cells secrete TNF, what will this do?
what will IL-4 secreted by TH 2 cells do to B cells? what will it do to other T helper cells?
it causes them to secrete IgE
causes other T helper cells to differentiate into TH 2
what will IL-5 secreted by TH 2 cells do?
activation of eosinophils
What do eosinophils do?
protect against parasites (helminths)
cytokines from TH 2 will inhibit activation of who?