Respon Imun adaptif

Respon Imun adaptif

Imunitas yang diperantarai oleh sel T Respon imun humoral

Dinamika imunitas adaptif Imun sistem mukosal

Sist immun innate

Sist imun adaptif

Sel T naive

Sel T efektor pathogen

Patogen ↑↑

Primingcell T

APC

The activation of naïve T cells is controlled by a variety of signals

• signal 1: co-stimulatory molecules

• Signal 2: ligands on T cells

• Signal 3: cytokines that control differentiation into different types of effector cells

MHC Sel T naive

APC : dendritic cells

• Dendritic cells  process antigens from a wide array pathogens

Immature dendritic cells

Signal 1 Signal 2

Cytokine: i.e. IL-12

APC: Macrophage

• Macrophage  do not present antigen mainly to activate naïve T cells  rather to make use of the effector functions of T cells

• Macrophage  phagocytosis , pinocytosis

• Activated macrophage  expressed MHCII and B7

• Macrophage is more important for expanding primary or secondary response already

initiated by dendritic cells

APC:B cells

• B cells  bind specific soluble molecules  receptor mediated endocytosis

• Activated B-cells 

– Present antigen peptide antigen as : peptide: MHC II complexes

– expressed B7

• Activated B-cells do not present antigen mainly to

activate naïve T cells  rather to make use of the

effector functions of T cells

Priming naïve T cells by pathogen - activated dendritic cells

• Signal 1  antigen-specific signals derived :

– interaction of a specific peptide:MHC complex with the T-cell receptor.  activating naïve T cells

• signal 2 : ligation of co-receptor-CD4 or CD8-is  stimulate the T cell to fully proliferate and differentiate into effector T cells T cells survival

• Signal 3: cytokines  T cells

differentiation

Signal 1

• Driven by IL-2 & IL2 receptor

Signal 2 : co-stimulatory pathway

CLTA-4 : inhibitory receptor for B7 molecules

T-cell tolerance to antigens – due to lack of co-stimulation reaction

Proliferating T cells differentiate into effector T cells that do not require co-stimulation to act

Cell surface molecules alteration in activated T- cells

CD8-T cells activation

• Activation of naïve CD8  need more co-stimulatory activity

• Two ways of CD8 T cells activation:

– Mature dendritic cells with high intrincsic co-stimulatory activity  induce CD8 T cells

– Need effecter CD4 effector T cells :

APC activate CD4 T cells CD8 T cells

Effector CD4 T cells

Signal 3

• Signal 3  determine cell differentiation of effector

CD4 cells

Signal 3: Cytokine

The effector functions of T cells are determined by the

array of effector molecules that they produce

T cell mediated cytotoxicity

Macrophage activation by T _H 1 cells

• Activation of macrophages by T

_H

1 cells promotes microbial killing and must be tightly regulated to avoid tissue damage

Toxic to pathogens + host cells + protease

Granulomas form when an intracellular pathogen or its constituents cannot be totally eliminated TBC