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
