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
