What surface markers identify CTLs?
CD3+ CD8+ recognizing antigen on MHC I
What are the main targets of CTLs?
Virus-infected cells and tumor cells
Besides killing what cytokine do CTLs mainly secrete?
IFN-γ
How are naïve CTLs activated?
Via cross-presentation on APCs often requiring TH help
Once activated do CTLs require co-stimulation to kill?
No
What are the two main mechanisms of CTL killing?
Granule exocytosis and Fas/TNF-mediated apoptosis
What do perforin and granzymes do?
Perforin forms pores and granzymes activate caspases leading to apoptosis
Which CTL ligands trigger extrinsic apoptosis?
FasL TNFα LTβ
How long do memory T cells live compared to effector T cells?
Months to years vs weeks to months
Do memory cells require antigen exposure for survival?
No
What cytokine is essential for memory cell maintenance?
IL-7
Bc the 7 has a flat top so it’s maintained
How do memory cells respond compared to naïve cells?
Faster and stronger
Do memory T cells require more or less co-stimulation than naïve T cells?
Less
Where can memory cells migrate to?
Peripheral tissues like skin
What transcription factor characterizes TREG cells?
FoxP3
What cytokines do TREGs secrete?
IL-10 and TGF-β
What is the main function of TREGs?
Maintain peripheral tolerance
What co-stimulatory molecule do TREGs express to inhibit T cell activation?
CTLA-4
When you’re on a track, you don’t want a CLA, so you deactivate it
How are TREGs generated?
In the thymus (self-antigen) and in the periphery (self and foreign antigen recognition)
What receptor do TREGs express at high levels?
IL-2R (CD25)
Why is IL-2 important for TREGs?
They rely on IL-2 for survival and deprive other T cells of it
What does IL-2 stimulate in T cells?
Proliferation differentiation survival and cytokine production
Which protein does IL-2 upregulate to prevent apoptosis?
Bcl-2
How does IL-2 act?
Autocrine and paracrine
