differentiation and functions of CD8 effector cells Flashcards
Extracellular antigens are processed and presented within class II MHC via the classical pathway, but they are also presented in association with ? because of cross presentation
class I MHC
CD8+ T cells are activated by mechanisms that involve_____ of antigens to CD8+ cells.
Cross-presentation
CD4+ helper T cells produce cytokines (IL-2) that stimulate
CTL differentiation
CD4+ helper T cells enhance the ability of APCs via______ to stimulate CTL differentiation
CD40L (on T cell) binding to CD40R (on APC)
Naive CD8+ T cells recognize which kind of Antigens presented by DC’s in the Lymph nodes?
peptide
Effector CD8+ CTLs are activated by the antigen in?
Peripheral tissues
activated CTLs mostly secrete this cytokine to potently activate macrophages?
IFN-gamma
similar to activation of Th1 cells, the molecular events in CTL differentiation involve?
transcriptional factor T-bet
T-bet regulates transcription of genes encoding for which proteins?
Perforin, Granzyme B, and IFN-gamma
CD4+ helper T cells are required for CD8+ T cell responses when weak innate immune reactions are evoked by?
latent viral infections, organ transplants, and tumors
Which cells are more important for the generation of CD8+ memory T cells than for the differentiation of naive CD8+ T cells into effector CTLs?
CD4+ helper T cells
which cells provide signal 3 by secretion of cytokines in CTL activation?
CD4+
activated CD4+ Th cells express?
CD40L
CD40-CD40L binding up regulate the expression of ____ on professional APCs
CD80/CD86
IL-2 promotes proliferation and differentiation of ? into CTLs and memory cells
CD8+ T cells
after activation of CD8+ T cells, they express high levels of?
alpha subunit of IL-2R
IL-2R shares a common receptor component with IL-15 and IL-21
Gamma chain
IL-12 and type I IFNs stimulate the differentiation of naive CD8+T cells into?
effector CTLs
local release of IL-2 can lead to activation of T cells which results in?
up-regulation of both cytokine and its receptors
defect in the common receptor chain Gamma
……
without IL-12, these cells are exhausted and decrease in number
CD8+ T cells
IL-12 activates these cells
activates NK cells
the primary source of IL-15 is found in?
activated tissue macrophages and mature DCs
IFN-gamma is an important component of?
anti-viral protection by up-regulating Antigen presentation of viral targets by infected cells
activated CTLs secrete these pro-inflammatory molecules
TNF-beta, IFN-gamma, cytotoxic perforin and granzymes
in chronic viral infections, responses of CD8+ T cells may be initiated but gradually extinguished. what is this phenomenon and what are the inhibitory molecules?
Exhaustion. CTLA-4, PD-1
PD-1 mediated T cell exhausion may contribute to?
chronicity of HIV and Hep C viral infections
perforin and granzymes are secreted into?
the synapse formation to Antigen or infected cell
what is the purpose of the immunologic synapse?
ensures that normal bystander cells are not injured by CTLs reacting against infected cells. no collateral damage.
Do all cells express Fas?
yes
FasL is expressed on activated CTLs to engage Fas on the surface of target cells to induce?
apoptosis
Perforin is a membrane-perturbing molecule that is homologous to?
C9 complement protein
granzyme B activates this enzyme to trigger apoptosis
Caspase-3
binding of FasL to Fas recruits ____ through the ____ to convert to the active form of the enzyme _____
Procaspase-8. FADD adaptor. Caspase-8
type I T cells use caspase-8 to
directly cleave caspase-3
in type II cells, like virus-infected hepatocytes, caspase 8- cleaves Bid to stimulate ?
cytochrome c from mitochondria
Cytochrome c and apoptotic peptidase activating factor 1 (Apaf-1) uses ATP to activate caspase 9 which activates?
caspase-3
macrophage activation by Th1 cells is an important immune mechanism in eliminating
bacteria which resist lysosomal degradation
Th1 cells make IL-3 and GM-CSF, which
stimulate macrophage production in the bone marrow
