T-Cell Immunity Flashcards
Which antigen presenting cells activate T cells?
Dendritic Cells
What are the two types of dendritic cells?
1-Conventional dendritic cells
2-Plasmacytoid dendritic cells
Which type of dendritic cells deal with all pathogens, express all TLRs except TLR-9 and prime Naive T cells?
Conventional dendritic cells
Which dendritic cell type deals with viruses, expresses TLR-7 and TLR-9 and releases type I interferons?
Plasmacytoid dendritic cells
Immature dendritic cells in peripheral tissues encounter pathogens and are activated by what?
PAMPs
TLR signaling induces expression of what to enhance processing of pathogen-derived antigens?
CCR7
*binding of CCL19 and CCL21 by CCR7 target the DC to lymph node
CCR7 directs migration into lymphoid tissues and augments expression of what 2 things?
- Co-stimulatory molecules (B7)
- MHC molecules
Where does the clonal expansion of B and T cells take place?
Germinal centers of Lymph nodes
____% of lymphocytes are CD4 T cells, ____% are CD8, ___% are B cells, ___% are NK cells and ____% are NK T cells
50, 25, 10, 10, 5
Where are circulating naive T cells exposed to antigens?
Lymph nodes
What membrane proteins binds dendritic cell ICAM-1 with low affinity?
LFA-1
*allows for subsequent TCR which sends a signal to LFA-1 if binding is good to change conformation and prolong cell-cell contact
LFA-1, ICAM-1 and talin are what kind of molecules?
Adhesion molecules
*part of the p-SMAC
TCR, CD2 CD4, CD8, CD28 and PKC-0 are what kind of molecules?
Signaling molecules
*part of the c-SMAC
What three signals are required for T cell activation?
1-T cell receptor (peptide recognition, MHC I/II, CD8/4)
2-Co-stimulatory molecules (survival signal, B7-CD28 required for activation)
3-Cytokines (paracrine/autocrine, propagation, differentiation and IL-2)
What co-stimulatory binding molecules are required for T cell activation?
B7-CD28
Which chemokine drives clonal expansion?
IL-2
*Activated T cells express high-affinity IL-2 receptors and secrete IL-2
What binds B7 receptors on T cells to inactivate them?
CTLA-4
*binds 20 fold stronger than CD28
What are 4 adhesion molecules of a CD4 T cell?
1-L-selectin (resting)
2-VLA-4 (activated
3-LFA-1 (resting, but more so for activated)
4-CD44 (resting, but more so for activated)
Which 3 cell surface molecules are signaling molecules in CD4 T cells?
1-CD2
2-CD4
3-TCR
*all in active and resting
Which two cell-surface molecules are proteases in CD4 cells?
1-CD45RA (resting)
2-CD45R0 (activated)
Which type of cells do not die once effector function is complete, kill repeatedly, only kill cells expressing targeted peptide via MHC I and differentiate into effector and memory cells?
CD8 T cells
What are two ways to activate naive CD8 T cells?
1-Dendritic cell infected with virus sends strong signal to stimulate self proliferation through IL-2 production
2-Dendritic cell infected with virus activates CD4 to secrete IL-2 and drive virus specific CD8 to express IL-2 receptors
What are three enzymes used by CD8 T cells to kill?
1-Perforin (makes holes)
2-Granzymes (serine proteases, activated caspase mediated apoptosis)
3-Granulysin (antimicrobial)
What are 4 roles of Th cells?
1-Enhance innate and adaptive immunity
2-Regulatory T cell arm
3-Targeted
4-Direct and indirect effector functions
T-Bet transcription factor is the result of interleukin signaling in a naive Th cell and results in the production of which cells?
Th1
*cellular mediated immunity. Produce IFN-y
GATA-3 transcription factor is the result of interleukin signaling in a naive Th cell and results in the production of which cells?
Th2
*Humoral immunity. Produces IL-4, IL-5 and IL-13
What 3 factors are involved in differentiation of Th Cells?
1-Cytokine induction
2-Transcription factor
3-Effector cytokines (often act in a positive feedback loop)
IL-12 are associated with?
Macrophages
IFN-y are associated with?
NK cells
IL-4 are associated with?
Basophils
What are the 5 subtypes of T Helper cells?
1-Th1 2-Th17 3-Th2 4-Tfh 5-T reg
Which type of T helper cells activate macrophages and of which IL-12 and IFN-y are characteristic?
Th 1 cells
*T-bet transcription factor
Which type of T helper cells enhance neutrophil response and of which IL-17 and IL-6 are characteristic?
Th 17 Cells
*ROR-yT transcription factor
Which type of T helper cells Activate cellular and antibody response to parasites and of which IL-4 and IL-5 are characteristic?
Th 2 cells
*GATA3 transcription factor
Which type of T helper cells activate B cells maturation of antibody response and of which IL-21 is characteristic?
Tfh cells
*Bcl6 transcription factor
Which type of T helper cells suppresses other effector T cells and of which TGF-B and IL-10 are characteristic?
T regulatory cells
*FoxP3 transcription factor
Bacteria stimulating TLR4 or TLR 5 as well as viral stimulation of TLR3, 7, 9 lead to what?
IL-12 production and Th1 differentiation (produces IFN-y)
Fungi stimulating Dectin-1 leads to what?
IL-6 and IL-23 production and Th17 differentiation (produces IL-17)
Helminth stimulation of TILR2/1 leads to what?
IL-10 production and Th2 differentiation (produces IL-4, 5, and 13)
Fungi stimulation of TLR 2/6 leads to what?
Il-10, RA and TGF-B production and T reg differentiation (produces IL-10 and TGF-B)
Which cells kill virus-infected cells?
CD8 Cytotoxic T cells
Which cells help macrophages suppress intracellular infections?
CD4 Th 1 cells
*Activated macrophages express co-signaling ligands (B7), kill intracellular pathogens, release cytokine and antimicrobial effectors and present antigens
Which cells help basophils, mast cells, eosinophils and B cells respond to parasite infections?
CD4 Th 2 Cells
Which cells help B cells become activated, switch isotope and increase antibody affinity?
CD4 Tfh Cells
Which cells enhance the neutrophil response to fungal and extracellular bacterial infections?
CD4 Th 17 cells
Which cells suppress the activities of other effector T-cell populations?
CD4 T regulatory cells
A compact aggregate of leukocytes that sequester a pathogen and can result in chronic inflammation are called what?
Granuloma
*Th 1 cells form granulomas when pathogens cannot be cleared.
What does secretion of IFN-y and CD40 by Activated Th1 cells do?
Activates macrophages to destroy engulfed bacteria
What does secretion of Fas ligand or LT-B by Activated Th1 cells do?
Kills chronically infected cells, releasing bacteria to be destroyed by fresh macrophages
What does secretion IL-2 by Activated Th1 cells do?
Induces T cell proliferation, increasing numbers of effector cells
What does secretion of IL-3 and GM-CSF by Activated Th1 cells do?
Induces macrophage differentiation in the bone marrow
What does secretion of TNF-a and LT-a by Activated Th1 cells do?
Activate endothelium to allow macrophage diapedesis at infection site
What does secretion CXCL2 by Activated Th1 cells do?
Causes macrophages to accumulate at site of infection
What do Th 2 cells promote?
Tissue protection and repair
*Increase mucus, enterocyte turnover, eosinophil activation, IgE cirulation (parasites), mast cell binding/diarrhea to expel helminths
Which cells recruit neutrophils, produce antimicrobial peptides and are involved in tissue repair?
Th 17 cells
*Enrich the gut. Persistent Th 17 cells involved in autoimmunity.
