56-Effector Functions Flashcards
activation of T cells
happens in secondary lymphoid tissues
function of secondary lymphoid tissues
activate T cells
localize antigen to rare antigen specific t cell
entry of t cells into lymph nodes
through high endothelial venules or lymyphantics
CCR7
migration into T cell zone of lymph node
sphingosine 1 phosphate
high concentration in blood
low concentration in SLO
what controls migration of t cells in and out of SLO
Expression of sphingosine 1 phosphate receptor
move toward high concentrations of s1p (blood)
activation of receptor causes down regulation and t cells moves back to SLO
changes in # and phenotype of t cell
caused by infection
1-activation by maturation of dendritic cell migrating to lymph node and presenting antigens to MHC
2-expansion of T cells that respond to antigen
3-differentiation and migration to infection
4-contraction of cells after clearance of infection
5-memory t cells form
DC licensing
upregulation of CCR7 to migrate into t cell zone of lymph node which have ligands for CCR7 (CCL19 and 21)
CCL19 and CCL 21
ligands for CCR7 in T cell zone
activation of t cell
Requires 3 signals
1- from activation of TCR using MHC/antigen, needed for activation
2- from costimulatory receptors for survival using CD28 and B7.1 and B7.2
3-from cytokines from APC required for differentiation
what controls activation and differentiation
costimulatory receptor activation
coactivation of TCR and CD28 increase CD40L which activates CD40 to drive costimulatory receptors
Expansion of T cells
after TCR recognizes antigens
CD4 expand 10,000x in 10 days
CD8 expand 50,000x in 10 days
CD69
promote degradation of S1P receptor during T cell activation
keeps T cells in SLO
during maturation and expansion the CD69 is reduced so T cells can leave now that they have S1P receptors again
migration of T cells to infection
like inflammation but selectins are on the t cell not the venule
TLR produces TNF and IL-1 to activate endothelium
venule has selectin ligand, chemokines, and integrin ligand
t cell has selectin, chemokine receptor, and integrin
selectin=rolling
chemokine=upregulation of integrin
integrin=adhesion and migration
Th1 CD4
fight intracellular pathogens
release IFN-y to enhance macrophages, NK cells, and CD8
Th2 CD4
fight large parasites and mucosal pathogens
release IL-4 to activate macrophages and b cell switch to IgG and IgE
release IL-5 to activate eosonophil and b cell switch to IgA
release IL-13 to promote mucous secretion and peristalsis
IFN-y
released by Th1 CD4 to enhance macrophages, NK cells, and CD8
IL-4
released by Th2 to activate macrophages and b cell switch to IgG and IgE
IL-5
released by Th2 to activate eosonophil and b cell switch to IgA
IL-13
released by Th2 to promote mucous secretion and peristalsis
Th17
fight small extracellular pathogens
release IL-17 to activate neutrophils and produce antimicrobial peptides
release IL-22 induce keratinocytes to promote epidermal hyperplasia
release IL-21 to activate CD8 cells, class switch B cells, differentiate NK cells
IL-17
released by Th17 to activate neutrophils and produce antimicrobial peptides
IL-22
released by Th17 to induce keratinocytes to promote epidermal hyperplasia
IL-21
released by Th17 to activate CD8 cells, class switch B cells, differentiate NK cells
CXCR5
expressed by CD4 T cells to migrate to B cell zone of SLO
this produces signals (cytokine IL-21) to enhance function of B cells
Proliferation and differentiation of CD8
into effector CD8 cells
stimulated by antigen presenting cells (antigen/MHC and costimulatory molecules)
release IL-2 to drive T cell proliferation
leave lymph nodes and kill
IL-2
T cell proliferation
Activation of APC
using CD4 T cells
express costimulatory ligands, release IL-2, stimulate CD8 T cells
CD8 killing mechanisms
express Fas ligand that activate Fas receptor on target cell
release perforin to form pores
release granzymes
IFN-y
inhibit viral replication
activate macrophages
increase MHC class 1
TRN-a
enhance target cell killing and activate macrophages
types of memory T cells
Central memory
effector memory
resident memory
central memory T cells
migrate to SLO, act like naive T cells, last for decades
effector memory T cells
migrate to SLO or non lymphoid tissues, last for 1 year
resident memory T cell
do not migrate
stay where they first reside
easily activated for rapid response to infection