L9 - Activation of T cells 1 Flashcards
where do activated dend cells enter the the lymphatic system from
afferent lymph vessel
via CCR7 (on DC) to CCL21 (on lymph node) attraction
HEV
high endothelial venules
HEVs enable lymphocytes circulating in the blood to directly enter a lymph node
what chemokine interaction allows T cells to be attracted to lymph nodes
CCR7 to CCL21 (on HEVs)
where do CD4tcells and DCs communicate in lymph node
paracortex
what other way can DC pick up antigen
DC present in the lymph node
so free antigen can flow past resident DCs
why is it important that recognising antigen alone is NOT enough to activate tcell
- some antigens presented are self or harmless
so this would trigger autoimmune disease or allergy
what else is needed for activation
co-stimulatory molecules
example of co stimulatory molecules
CD28 on tcell
with
either CD80 or CD86 on DC
what might cause a DC to upregulate its co stimulatory molecules expression
DCs recognsie PRRs from pathogens
which upregulates CD80
and also upregulates MHCII
why is cell adhesion important
so t cell keeps in contact with DC to support full activation
whats an important cell adhesion moleucle expressed by DC
ICAM-1
what on the tcells binds to ICAM-1
LFA-1 intefrin
this allows loose binding which allows tcell to sample the antigen
what happens if the tcell recognises the antigen after intial interaction with DC
intracellular signals that make LFA1 and ICAM1 bind strongly
and then more t cell aned MHC II interactions can occur
what is this point of contact between tcell and DC known as
immunological synapse
what do the clusters of molecules at the interface form
supramolecule activation clusters
SMACs
