Linking Innate and Adaptive Immunity 2 Flashcards
do DCs only present 1 antigen?
no, they can present multiple antigens at once, multiple parts of an antigen
what is the role of selectins? what type of molecule is it?
selectins are responsible for binding and rolling of T cells
what do chemokines bind to? what type of chemokine?
CCL21 chemokine activates CCR7 receptor on lymphocyte
what happens once CCL21 binds CCR7 on lymphocyte?
CCR7 receptor is activated so lymphocytes can make integrins
what is the role of integrin? what type of molecule is it?
integrins are responsible for tight binding that causes the lymphocyte to migrate
what allows T cells to roll along endothelial surface?
light attachment of SELECTIN on T cells to ENDOTHELIAL CELLS of HEV
what vessel carries T cells to lymph nodes?
HEV
what vessel carries T cells to Peyer’s patch?
mucosal epithelium
what is the main, general role of selectins?
“leukocyte homing”
aka bind receptors to target T cells to lymphoid tissue
what are the 4 steps of lymphocyte migration? and the molecules involved?
- ROLLING –> selectins at HEV allow lymphocyte to roll along endothelium
- ACTIVATION –> CCL21 secreted by HEV binds CCR7 and leads to conformation change in integrin
- ARREST + ADHESION –> integrin changes conformation to bind ICAM and keep lymphocyte in one place
- DIAPEDESIS –> lymphocyte migrates across endothelium
how do DCs attract T cells to them? where does this occur?
in the lymph node, DCs secrete chemokines to attract T cells to them
what is the function of fibroblastic reticular cells? where is it located?
make a mesh surrounding lymph node
they secrete CCL21 chemokines which attract T cells and DCs to lymph nodes
what happens to the movement of naive T cells before and after they bind the DC?
before: T cells move around a lot
after: T cells stop moving once antigen binds MHC on DC
what does the interaction of T cells with the antigen depend on? (4)
- quality of antigen
- quantity of antigen
- availability of antigen
- activation state of DC
how long do T cells bind to DCs?
> 8h
why won’t dying DCs interact with T cells?
if they are dying, they won’t be able to survive the 8h-long interaction
how many T cells “survey” a DC per hour?
5000 T cells per hour
how long do T cells spend circulating and looking for their antigen?
1-24h
do T cells stay at one lymph node while searching for an antigen or travel to many lymph nodes?
can search in as many lymph nodes it takes to find antigen
when do T cells stop searching for antigen?
until they die or find one
what happens once the T cells have found their antigen? how long does this take?
they proliferate and differentiate for 4 days
what occurs when your lymph nodes are swollen?
T cells are proliferating
what does it mean to say the immune system is dynamic?
it is constantly dealing with many events in parallel and many processes can overlap, change locations, and influence each other
what is the only thing that T cells recognize?
peptide fragments of Ag bound to self molecules of MHC on APC
what makes T cells different from each other?
they have clusters of differentiation co-receptors on their surface
what type of effector cells do CD8+ T cells become?
Cytotoxic T lymphocytes
what type of effector cells do CD4+ T cells become?
Helper T cells
what are the 5 types of helper T cells?
- TH1
- TH2
- TH17
- Treg
- Tfh
what determines the type of helper T cell it becomes?
determined by the cytokines that act on the cell
what is the difference btwn each type of T cell?
they have a distinct cytokine profile that regulates distinct activities within the body
describe the activation of CD4+ T cells (5)
- APC releases cytokines and presents antigen on MHC II
- CD4+ T cell binds antigen using TCR
- CD4+ T cell binds MHC II using CD4
- CD28 binds CD80/86
- CD4+ T cell becomes T helper cell (effector cell)
describe the activation of CD8+ T cells (5)
- APC releases cytokines and presents antigen on MHC I
- CD8+ T cell binds antigen using TCE
- CD8+ T cell binds MHC I using CD8
- CD28 binds CD80/86
- CD8+ T cell becomes cytotoxic T cell (effector cell)
what is the type of effector T cell associated to? why?
the type of effector T cell is associated with the type of PAMP that the DC was exposed to
because the PAMP affects the cytokines that the DC produces and therefore the type of effector cell that arises
