T CELL MEDIATED IMMUNITY

Dewi K Paramita

Deparment of Histology and Cell Biology

Faculty of Medicine UGM

deardesay@yahoo.com

T cell completed the development in thymus

Native T cells are activated by antigen presented by dendritic cells

Adaptive immunity

Cellular

immunity

The Role of Effector T cells

Nave T cell Activation

T cell entry into cortex of

lymph node

T cell meet antigen

presented by dendritic

cell

Activated T cell

diiferentiate to effector

cells and exit the lymph

node

Different T cell type activated by

different pathogen

Signal needed for CD4 T cell

activation

1. Activation of nave T cells

by CD4 co-receptors

2. Co-stimulatory signal

(CD28-B7) increase survival

of T cells that has received

signal 1

3. Differentiation of T cell

depend on the signal

deliver by APC

Activated T cells bind IL-2 with high

affinity needs for proliferation

Signal 3 delivered by APC

Signal needed for CD8 T cell

activation

Effector T cells can respond to their target cells without co-stimulation

Prevention of immune response

to self antigen

Both antigen-specific

signal and co-stimulatory

signal are crucial in

preventing immune

response to self antigen

Most CD8 T cells responses

require CD4 T cells

Different effector molecules produced by different types of

effector T cells subset, which deal with different classes of

pathogen

Different effector molecules produced by different types of effector T

cells subset, which deal with different classes of pathogen

Interaction of T cells with target cells initially

involve nonspecific adhesion molecules

Cellular polarization of T cells during

specific antigen recognition

Cytotoxic T cells induce target cells to undergo

apoptosis

Cytotoxic T cells act by releasing cytokines

T cell mediated cytotoxicity

Cytotoxic CD8 T cells induce

apoptosis in target cells

Cytotoxic effector proteins released

by cytotoxic T cells

Cytotoxic effector proteins deliver granzymes

into cytosol of target cells to induce apoptosis

Cytotoxic T cells only kill target cells

bearing specific antigen

TH1 cells have a central role in macrophage

activation

Macrophage activation by TH1 cells promotes

microbial killing and tightly regulated to

avoid tissue damage

TH1 coordinate the host response to

intracellular pathogens

Macrophage activation by TH1 cells

Macrophage activation by TH1

Bacterial peptide specific TH1

contacts an infected macrophage

T cells secrete IFN- & express CD40 ligan

Activate macrophage to kill

intravesicular bacteria

Immune response to intracellular bacteria

is coordinated by activated TH1 cells

Conclusion

Activated T cell undergo differentiation depend on the signal

delivered by APC :

TH1 (IL-12, IFN-)

TH2 (IL-4)

Treg ( TGF-)

Different type of effector T cells deal with different classes of

pathogen, and produce different type of effector molecules :

CD8 T cell (CTL) intracelluler pathohgen (virus)

CD4 T cell : extracellular pathogen

CD8 T cells kill virus infected cells by inducing apoptosis and cytokine production

TH1 activate macrophages to kill intravesicular bacteria.

Thank You