Flashcards in Differentiation And Functions Of CD4+ T Cells Deck (79):
Alpha beta TCRs recognize and bind to __.
Peptides presented within the MHC molecules and MHC itself.
These cells also express either CD4 or CD8 co-receptors.
Where does activation of T cells occur?
In the lymph nodes.
What are langerhans cells?
Immature dendritic cells which do not express high levels of B7.
They stimulate naive T cells.
What does Ag recognition involve?
Clustering of TCRs.
What is the activation of T cells initiated by?
A signaling cascade after TCRs recognize specific Ag.
What is needed to activate a T cell?
TCR, CD4 or CD8 and CD3.
CD4 for T helper cells
CD8 for CTLs
When the TCR is engaged and activates T cells, the T cell must:
Receive a co-stimulatory signal.
____ can be considered as an "amplifier" that improves signaling of T cells.
This involves B7 and CD28.
With co-stimulation, 100 fold fewer of clustered TCRs are needed for activation.
Once T cells are Ag-activated, what do they produce?
IL-2 and IL-2R, which leads to cell proliferation.
The result is the expansion of the clone of T cells that are specific for the Ag.
What do T cells differentiate into?
Effector cells or memory cells.
What drives proliferation of T cells, and is also called the "T cell growth factor"?
True or false: naive T cells do not have IL-2 receptor (IL-2R) expressed on their surface.
True or false: activted T cells produce a large amount of IL-2 and express IL-2R.
___ enhances resistance of activated T cells to apoptosis.
How do effector T cells migrate through blood vessels in peripheral tissues?
They bind to endothelial cells that have been activated by cytokines produced in response to infection in these tissues.
CD4+ cells recruit and activate phagocytes. What do the phagocytes destroy?
What do CD8+ lymphocytes kill?
True or false: each subset of T helper clls tends to oproduce a set of particular cytokines.
What do Th1 cells activate?
A cell-mediated immune response.
What do Th2 cells activate?
An Ab-mediated immune response.
What are Th17 cells involved in?
Inflammation and anti-bacterial response.
Why are PRRs important for innate and adaptive immunity?
Pathogen recognition by immature DCs through PRRs is an important bridge between innate and adaptive immunity.
What is the result of PRR signaling?
Activation and maturation of antigen-presenting cells (APCs)
APC processed antigen is presented to what cells?
Naive Th0 cells.
Secreted IL-12 assists the development and differentiation of what type of helper cell?
What are four main classes of CD4+ cells?
What causes differentiation of Treg cells?
IL-2 + TGF beta
What are the functions of Treg cells?
Suppresses tumor immunity
Promotes immune tolerance
Maintains lymphocyte homeostasis
What cytokine activates Th1?
What are the functions of Th1?
Promotes tumor immunity
What acitvates Th2?
What are the functions of Th2?
What activates Th17?
What are the functions of Th17?
Breaks immune tolerance
What immune reactions are stimulated by Th1 cells?
What immune reaction is associated with Th2?
Mast cell, eosinophil activation,
Alternative macrophage activation
What immune reactions are associated with Th17?
What is the host defense associated with Th1 cells?
What is the host defense associated with Th2 cells?
What is the host defense associated with Th17?
Extracellular bacteria; fungi
What is the function of TGF-beta?
It functions mainly as an inhibitor of immune responses
What is involved in the development of a Th1 cell?
IL-12 and IFN-gamma activate a T cell.
T-bet, STAT4 and STAT1 activate a Th1 cell
What is involved in the development of a Th2 cell?
IL-4 activates a T cell.
GATA-3 and STAT6 activate a Th2 cell
What is involved in the development of a Th17 cell?
A dendritic cell uses IL-1, IL-6, IL-23 and TGF-beta to activate a T cll.
ROR gamma t and STAT3 activate a Th17 cell.
What is IL-12 produced by?
DC and macrophages.
In the development of Th1 cells, what produces IFN-gamma?
What is the function of IFN gamma in the development of Th1 cells?
It amplifies the Th1 repsonse and inhibits the development of Th2 and Th17 cells.
In the development of Th2 cells, what produces IL-4?
Activated T cells or by mast cells and eosinophils.
These activate GATA-3 and STAT6, which stimulate the differentiation of naive CD4+ T cells to the Th2 subset.
What is the function of IL-4 during the development of Th2 cells?
It amplifies the response (development of Th2 cells) and inhibits the development of Th1 and Th17 cells.
What transcription factors are activated by IL-1, IL-6 and TGF beta?
ROR gamma t and STAT3.
These stimulate the differentiation of Th17 subset.
What do ROR gamma t and STAT3 regulate the production of?
IL-21. This amplifies generation of Th17 cells.
What cytokine is very important in the differentiation of Th17 cells?
What is the function of IL-17?
It protects from extracellular pathogens and is involved in tissue inflammation and autoimmunity.
How does TGF-beta promote the Th17 response?
By suppressing Th1 and TH2 cells, both of which inhibit the Th17 differentiation.
What is the role of oxygen species, nitric oxide, and increased lysosomal enzymes in cell-mediated immunity?
Killing of microbes in phagolysosomes
What is the role of the secretion of cytokines and chemokines in cell-mediated immunity?
Th1 differentiation, IFN gamma production
What is the role of increased expression of B7 costimulators and MHC molecules?
Increased T cell activation (amplification of T cell response).
What are functions of Th2 cells?
Mast cell degranulation
Intestinal mucus secretion and peristalsis
Alternative macrophage activation (tissue repair)
What is the funciton of ROS, NO and l ysosomal enzymes?
Phagocytosis and killing of many bacteria and fungi.
What is the role of chemokines (IL-1, IL-12, IL-23)?
What are the roles of IL-10 and TGF beta?
Anti-inflammtory effects, wound repair and fibrosis
What are the functions of Th17 cells?
Inflammation, neutrophil response
Increased barrier function
True or false: CD8+ T cells are activated by mechanisms that involve cross presentation of antigens to CD8+ T cells.
Where are CD8+ T cells activated?
In the LN by dendritic cells loaded with Ags exactly as CD4+ T cells are.
True or false: CD4+ helper T cells produce cytokines that stimulate CTL differentiation.
True or false: CD4+ helper T cells enhance the ability of APCs to stimulate CTL differentiation.
True or false: CD8+ T cells recognize antigen + costimulators on professional APCs, which results in CTL differentiation without helper T cells.
CTLs are activated to release their granule contents. What are in the granules?
Perforin and granzyme
What do CD8+ T lymphocytes secrete, and what does it activate?
They secrete IFN-gamma, which activates macrophages.
What do nontraditional gamma delta T cells have?
Gamma delta TCRs and CD3.
Most of them do not express CD4 or CD8 co-receptors.
Where are nontraditional gamma delta T cells most abundant in?
The intestine, uterus and the tongue
What are the functions of gamma detla T cells?
First line of defense
Bridging between innate and adaptive responses
Gamma delta T cells are considered a component of what type of immunity?
Rearrangement of TCR genes produces __.
True or false: NKT cells share properties and CD markers of both T cells and NK cells.
What do NKT cells recognize?
Self- and foreign lipids and glycolipids.
What is the role of activated NKT cells?
They produce large quantities of IFN-gamma, IL-4 and GM-CSF, as well as other cytokines and chemokines. They also rapidly release cytokines. They also promote or suppress different immune responses.
What occurs when there is a dysfunction or deficiency of NKT cells?
Autoimmunity (diabetes or atherosclerosis)
Progression of asthma.