T Cell-Mediated Immunity
Dr Alok TripathiDepartment of
[email protected]
3
EffectorT CellPathogenLocationAntigenPresentationTarget
CellActionCellularImmunityTc CD8cytotoxicCytoplasmInfected cell MHC
IInfected cellapoptosis Th1 CD4inflammatory
MacrophagevesiclesMacrophage MHC IIMacrophage activation to kill
pathogenHumoralImmunityTh2 CD4helperExtracellularAPC MHC IIB cell
antibody production
17
Ig SuperfamilyAdhesion MoleculeTissue DistributionIntegrin
LegendCD2 (LFA-2)T cellsLFA-3 on APCICAM-1 (CD 54)Activated
endotheliumdendritic cellsT cellsLFA-1 on T cellsMAC-1 on
macrophagesICAM-2 (CD102)Resting endotheliumLFA-1 on T cellsICAM-3
(CD50)Nave T cellsDC-SIGN on dendritic cellsLFA-3
(CD58)LymphocytesAPCCD2 on T cells
CD40P
mIgM & mIgD
APC TCRs
Ag MHC-IICD40L IL2,IL4, IL10, IL5, & IFN B7 & CD28
T Cell ActivationKillEndogenous AntigenActivate CTL KillInfected
CellExogenous AntigenActivate ThStimulateM
Endosomal Pathogens
Nave T Cell MHC-I~PeptideCD-8T CellMHC-IICD-4T Cell
Co-Stimulatory Signals
APCOnly professional APC (DC, NK & B- Cells ) have both
MHC-I;II and can deliver co-stimulatory signal
Proliferate & Differentiate
Perform their function when they encounter Target
cell-MHC~peptide
APC [B-Cell] ThY
AgYY
MHC-IIPB7CD-28TCRCD-40CD-40L CK CO-STIMULATORY SIGNALS
Nucleus
Singling CascadesProcessing & Presentation of Ag
T cells Anergy
APC=DC,M or B cells:DC deliver both signal and are the best APC
and are the responsible for the activation of the most of the nave
cells
CD-40LT-CellsAg & Co-Stimulatory SignalsActivated T
CellsExpress
Other receptors
Enhance Co stimulation
APC
CD-40To provide more co stimulation Activate M &B-
CellsFurther Interaction of APC & T Cells
The immune response therefore depends upon PUSH of the antigen
stimulation to activate T cells in to effectors cells and PULL of
negative signal that curtail T cells responseB7CTAL-4ICOS
4-IBB/CD-137
4-1BBLTo further activate T & APCLICOSInducible co
stimulator
