alpha beta T cells Flashcards
Priming phase of (alpha-beta) T cells: what is it similar to? what happens in this stage (generally)
this is the schooling phase of T cells; we teach them how to differentiate (antigen dependent in the lymph tissue ) to become memory and effector T cells
What cell takes an antigen to the lymphatic vessel? Why?
the dendritic cell. it goes to the lymph and then displays the antigen so that (hopefully) a T cell will come by and recognize it
during its course to the lymphatics, the dentritic cell displays more ___ because it changes its __ and ___
it displays more MHC class II because it changes its gene expression and morphology
MHC class II is for
CD4 T cell
MHC class II is for
CD8 T cell
what are two modes of infection that the CD4 cell works with?
receptor mediated endocytosis of bacteria;
macropinocytosis of bacteria or viruses
what are two modesof infection that the CD 8 cell works with
viral infection; more specifically viral antigens inside the cell or from transfer of viral antigens from another cell
where are microorganisms trapped
if in blood ==> spleen
if in mucosal tissues ==> lymph tissues
if in skin==> dendritic cells mature and trasnport to lymph
how do naive T cells get from blood to the lymph nodes
high endothelial venules OR from an aferent lymph vessel (only if its in the lymph system already)
what does L-selectin do
it captures T cell in the blood as it rolls along the blood vessel
what does CCR7 do
it recognizes the chemokine that are expressed in the lymph node endothelium
after the T cell attaches to L-selectin receptor and chemokine, what happens
it binds LFA-1 (receptor on T cell) to ICAM1 (on antigen presenting cell)
diapedesis happens after? end result?
happens after firm adhesion of the T cell to the endothelium; the lymphocyte leaves the blood and enters the lymph node
describe interaction between TCR and Ag/MHC
its is not strong enough to sustain contact between the T cell and the antigen presenting cell
describe the interaction between integrins and the TCR
these strengthen the interaction between the T cell and antigen presenting cell
T cells are dangerous and you don’t want them to just respond to one thing. what does it need for full activtion
it requires a signal from the T cell receptor AND the CD28
what receptor is expressed in all t cells
CD 28
what are the two receptors for B7 molecules? what cell highly expresses the B7 molecule
B7 (its on activated antigen present cells, but highly expressed by activated dendritic cells)
It will bind to either CD 28 or CTLA4
when is CTLA4 expressed?
its only expressed on the activated T cell
what does the CTLA4: B7 interaction do
it negatively regulates T cell activation, and limits the T cell activation and proliferation
what is anergy/anergic
these cells are frozen, or unresponsive…. like they don’t have any energy
What is one way a T cell can become anergic
if it recognizes an antigen presented on an immature APC (without B7). this is one way the body keeps T cells from recognizing self antigen
three types of professional antigen presenting cells and their locations
dendritic cell ==> T cell area of lymph node
B cell ==> follicle of lymph node
macrophage ==> the whole lymph node
what is one functino that ONLY the professional antigen presenting cells can do
express the B7 , and they express HIGH levels of MHC I and II
what Ag does a B cell present
soluble antigens;
toxin;
viruses
what Ag does a macrophage present
particulate Ag;
intracellular and extracellular pathogens
what Ag does a dendritic cell present
peptides;
viral antigens
allergens
where are macrophages are good at activating T cells
these are good at activated them during infection of inflammation
where are DCs good at initiating T cell differentiation
lymphoid tissues
what is B cell good at doing (with T cell)
it is good at presenting soluble antigens, which is important in receiving T cell help
what is something that the immature dendritic cell is good at
Mr dendritic cell is good at phagocytosis. (he is so skinny and eats everything). once he gets activated, though, he loses that ability
what makes a DC mature?
bacterial products; inflammatorn cytokines (TNF alpha)
mature DCs express what and migrate where?
CCR7
during the T cell activation, what does the CD4/MHCII initiate
Lck phosphorylates ITAM and ZAP; this initiates a cascade of signal transduction
what cell process do you need to memorize?
figure 8.16 in the notes
once the T cell is activated, what is produced
IL 2 and IL2R-alpha is induced for T cell proliferation
what does interleukin-2 do (IL2) - 3 things
- it induces T cell proliferation, and increased cytokines (IL4, IFN-gamma)
- B cell proliferation and antibody production
- NK cell proliferation and increased cytolytic activity
what does cyclosporinA and FK 506 do? when is this helpful?
these suppress the T cell and its activation by blocking IL2 production; this is used in organ transplantation
When the T cell is activated what are two receptors that are activated
(very late antigen) VLA-4 and CD45RO
when the T cell is activated what are two receptors that turn off
L-selectin and CD 45 RA
when the T cell is activated what are two receptors that remain unchanged
the CD4 and TCR
when the T cell is activated what are three receptors that are enhanced
LFA-1
CD2
CD44
why do the receptors change after activation
the function changes, so they change expression of adhesion molecules and chemokine receptors.
what do t helper cells do? (general)
promote cell mediated immunity
specifically they help macrophages to suppres intracellular infections
t helper cell 1 makes what cytokines
type I cytokines (IFN-gamma, and IL2)
what do t helper 2 cells do? (general)
they promote humoral immunity
specifically to help mast cells, basophils, eosinophils and B cells respond to parasites
what do t helper 17 cells do? (general)
they promote imflammation in multiple tissues
specifically they enhance the neutrophil response to fungal and extracellular bacterial infections
what is the IgE response for?
defense against parasites and allergic responses
what promotes the IgE response
Th2 cell
what are the cytokines that are made by T helper cell 17
IL 17 and IL 22
what are the cytokines that are made by T helper cell 2
IL 4,5,10,13 (there are others but he said these are impt)
what promotes/inhibits polarization of T helper cell1
promote = IL-12 and IFN gamma inhibit = IL-4 and 10
what inhibits/promotes t helper cell 2 polarization
promote = IL4 inhibit = IFN gamma
what inhibits/promotes t helper cell 17 polarization
promotion = IL 1,6, 23 inhibit = IL 4 and IFN gamma
what is the function of T FH cells
they help b cells become activated by producing IL 21, they switch B cell isotype (with IL4) and increase antibody affinity
cytotoxins that are produced by CD8 t cells
perforin
granzymes
granulysin
what does the t regulatory cell do
it suppresses the activities of other effector T cell populations
