lecture 5 Flashcards
T cells circulate via blood and lymphatics through?
secondary lymphoid tissue
the t cells binds to an antigen on an APC the t cell does what
proliferated and differentiates
after this binding the naive t cells become what cells
effector t cells or memory t cells
what is the effector function of CD8 cells
kill infected cells (cytotoxic)
what is the effector function of CD4 cells
secrete cytokines (helper t cells)
what do t cells go through to get to lymph node from blood
High endothelial venule (HEV)
t cells not activated exit the lymph node via what
the cortical sinuses
what ligand binds to its receptor on the surface of T cells to tell them where to go
chemokines
what allows the t cell to contact the APC initially to see if theres a peptide being presented that binds to the TCR
CAMs (cell adhesion molecules)
if there is recognition what happens
affinity of CAM interactions
T cell divides
differentiate to effector cells
what is signal 1
naive T cells receive a signal from TCR contacting MHC on APC
co stimulation (signal 2)
APC express co stimulatory molecules B7.1/2 which binds to what on the T cell
CD28
signal 3:
APCs release what
cytokines
the cytokines bind to the cytokine receptors and tell the T cell what?
what type of T cell it needs to become
what is the type of CAM on a CD4 t cell
LFA-1
what CAM does LFA-1 bind to on the APC
ICAM-1
if the naive t cell gets all 3 signals it becomes an
effector t cell
once T cells activated what what molecules do they release to turn off activation of T cells
ICOS and CTLA-4
what does ICOS do
binds to ICOSL on APC to induce cytokine secretion
what does CTLA-4 do
CTLA-4 binds to B7.1/2 better than CD28 so displaces CD28
antagonist of CD28 to limit the t cell response so effector cells dont keep getting made
mutations in CTLA-4 causes autoimmune diseases e.g
type 1 diabetes
signal 3 (differentiation)
what type of effector cells can CD4 t cells become
T helper 1
T helper 2
T helper 17
T follicular helpers
T regulatory cells
release of IL-4 from APC causes differentiation to which T cell type
T helper 2 cells
release of IL-12 and IFN-γ from APC causes
T helper 2 cells
TGF-β and IL-6 from APC causes
T heper 17 cells
IL-6 from APC causes
T fh cells
TGF-β from APC causes
T reg cells
mains dendritic cells are
DC2 and 3
specialised DC (DC1) take up and process exogenous antigens and present it on
MHC I molecules
this allows DC to activate which cells
naive CD8 T cells
once naive cells have become effector cells the no longer need
co stimulation so they can kill infected cells
macrophages prime funcion is what
to engulf pathogens
macrophages also express peptides on MHC class II and activate T cells, the T cells activates by a macrophage will make the macrophage
more active
B cells make antibodies more efficiently if they
get help from T cells
when T cells become activated they the IL-2 receptors have a higher affinity to IL-2
IL-2 binding to IL2R causes
lots of T cell proliferation
CD8 cells when activated become
cytotoxic cells
they kill cells expressing peptide/MHC class I complexes
CD4 cells when activated secrete
cytokines that help other cells
they are activated by recognising MHC class II complexes
