T cell activation, differentiation and memory Flashcards
What is a naïve T cell?
mature T cell but has not learned anything so has no memory so considered naïve
what three signals are required for T cell activation?
- TCR signaling
- costimulatory interaction
- cytokine signaling
what is TCR signaling?
provides and sets the stage for T cell activation
a) TCRab: peptide/MHC
B)CD4 OR CD8: MHC
C) adhesion molecules
what are costimulatory molecules?
co-stimulators on T cells CD 28
binding between CD80/86 (APC) and CD28 (T cell) needed for activation
lack of response means no activation of T cells
what are co-inhibitory molecules?
function to terminate T cell responses by turning off their activation
Engagement of CD-80/86 (APC) and CTL-4 leads to:
no response
Engagement of PD-1 and PDL1/2 leads to :
inactivation (anergy) of T cells in the periphery
what is anergy?
induction of non-responsiveness to further stimuli (functional inactivation of cells)
what does CTLA-4 bind to?
CD80/CD86
WHAT DOES PD 1 DO?
programmed cell death
what are cytokines?
activated different transcription factors that guide T cells to differentiate into various subsets
what is necessary for activation of T cells?
binding between B7 ad CD 28
what does T helper 1 cells do?
combats intracellular pathogens activates macrophages, IgG production
what diseases do Th1 cells have a role in?
autoimmune diseases, tissue damage associated with chronic infection
what does T helper 2 cells do?
combats helminth infection activates eosinophils, IgE production, alternative macrophage activation
what diseases does Th2 play a role in?
allergic reactions
what does T helper 17 cells do?
combats extracellular pathogens, bacteria and fungi in barrier tissues
what does Th17 role in disease?
organ specific autoimmunity
what is the polarization response?
each T cell subset produces cytokine that amplifies itself and inhibits others making the response increasingly polarized
T Helper 1 cells APC produce
IL-12
T Helper 1 cells activate:
T bet
T Helper 1 cells induce naïve T cells to ___________
differentiate into Th1 cells
what does Th1 produce
interferon gamma (INF y)
which activates macrophages
Th1 enhance what?
antigen presentation
cytokine production
nitric oxide production
killing of microbes
what reciprocal relationship do helper t cell 1 participate in?
activate macrophages
what stimulates macrophages to ingest microbes?
IFNg (gamma)
Th1 and IFNg mediate ____
antibody class switching
antibody class switching stimulates
production of IgG
IgG binds to Fc receptors on phagocytic cells to:
enhance phagocytosis
Th2 induces naïve T cells to differentiate into
Th2 cells, which is especially effective against worms
what do Th2 cells produce
IL 4, IK 5, IL 13
what class switching does Th2 allow?
IgE and IgG4
what does IgE do?
gE activates mast cells degranulation
what do cytokines IL 3 and 13 induce?
alternative pathway of macrophage activation
what does M1 macrophages do?
induced by ILR and IFNg
killing of bacteria/fungi
inflammation
what does macrophage M2 do?
anti-inflammatory effects
wound repair and fibrosis
Activation of transcription factor RORΥt Induces naïve T cells to
differentiate into
Th17 cells (induces inflammation)
Th17 produce which IL?
17 and 22
what do Th17 do?
recruit neutrophils, increase barrier function (like in GI tract)
what is critical for fighting a fungal infection?
Th17
