Lecture 13: Differentiation and Functions of CD8+ T Cells Flashcards
% of helper T cells and % of cytotoxic T cells out of T lymphocyte population
66% Helper T cells
33% Cytotoxic T cells
Activated CTLs contain
Lysosomes that contain perforin and granzymes
T-bet regulates what
Transcription of genes encoding perforin, granzymes and IFN-y
How do some EC antigens get presented in association with MHC I molecules?
Cross presentation- some viral Ags are released from phagosome in cytoplasm of DC and then presented with class I MHC (The same cross-presenting APC can display microbial peptides within class II MHC for CD4+ T cells)
Why does generation of CD4+ T effector cells precede appearance of CD8+ T cells
Because DCs need “education” which takes time.
Licensing of APC occurs when
CD4+ T cell delivers activating signals through CD40L/CD40 signaling and release of IFN-y to DC after it recognizes Ag presented by an MHC class II APC
Activated CD4+ T cells increase expression of
CD40L
Effect of CD40L/CD40 and IFN-y interactions
Upregulates expression of CD80/86 on DC and stimulates Ag cross presentation which makes them more efficient at inducing differentiation of CD8+ T cells
IL-2R shares the same y chain with what cytokines
IL-15R and IL-21R
Naïve CD8+ T cells proliferate in response to ___ and ___ signals, but also require ___ or___ for survival and development of optimal effector functions
Proliferate in response to TCR and CD28 signals, but also require IL-12 or IFN-y
IL-15 produced by what and is required for
DCs and tissue macrophages
Survival of memory CD8+ T cells
IL-21 is produced by what and plays a role in
Activated CD4+ T cells
Induction of CD8+ T cell memory and prevention of CD8+ T cell exhaustion
Key feature of IL-2
Autocrine loop through which it operates
15kDa peptide
Local release of IL-2 can lead to
Clonal expansion of T cells, which upon recognition of Ag presented by APC express a-subunit of IL-2R
Local release of IL-2 by activated CD4+ T cell leads to
Activation of nearby Ag-activated CD8+ T cells in a paracrine fashion
IFN-y is a ___dimer
Homodimer of 25kDa
IFN-y has ability to increase __________ expression on a range of cell types and induce expression of ______ on professional APCs
Increase MHC I expression on many cells
Induce expression of MHC II on professional APCs
IFN-y favors development of ___ and ___ cells and biases production of Ig ___ and away from Ig___
Favors development of Th1 cells and B cell differentiation
Production towards IgG and away from IgE
IL-12 promotes production of pro-inflammatory cytokines
IFN-y and TNF-b by CD4+ and CD8+ T cells
IL-12 stimulated CD8+ T cells compared to IFN-y stimulated T cells
IL-12 stimulated are more effective in controlling tumor and they maintain high numbers and function as compared to IFN-y stimulated cells
IL-12 also assists in prevention of ___ and activates
Prevents exhaustion of CD8+ T cells
Activates NK cells
Primary source of IL-15
Activated tissue macrophages and mature DCs
Exogenous IL-15 favors human ____ differentiation
Th1 T cell differentiation
IL-15 stimulates proliferation of ____ and ___
Memory CD4+ and CD8+ and naïve CD8+ T cells
