alpha beta T cells Flashcards
(57 cards)
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
