Antigen Presentation Flashcards
What is the term for something that causes the immune system to create antibodies specifically targeting that something?
Antigen
What is the term for an antigen that a given B cell’s receptors recognize?
Cognate Antigen
What is the part of the antigen that the antibody recognizes and attaches?
Epitope
What is the part of the antibody that recognizes and attaches to the epitope?
paratope
What does MHC stand for?
Major Histocompatibility Complex
Which MHC is associated with almost all cells of the body?
MHC I
Which MHC allows us to see what is being made in the cells?
MHC I
Which MHC is only associated with antigen presenting cells?
MHC II
Special cells eat protein (phagocytosis) outside of the cell, break it down, and present the fragments on the cell surface. Which MHC is associated with this process?
MHC II
Cells constantly break down proteins created within the cell and present them on the cell surface. Which MHC is associated with this?
MHC I
What are endogenous proteins?
proteins made in the cell
During Antigen presentation by MHC I, what type of proteins are constantly being broken down into fragments?
Endogenous proteins
What are cytotoxic lymphocytes associated with anitgen presentation by MHC I?
Killer T cells
During antigen presentation by MHC I, what are responsible for constantly inspecting the presented fragments?
Cyotoxic lymphocytes (Killer T cells)
What molecules bind to protein fragments created in the cell and bring them to the surface of the cell?
MHCs
Which MHC is most like a constantly updating billboard that advertises what is being made in the cell?
MHC I
What kind of proteins are presented by MHC I?
ordinary cellular proteins (enzymes and structural), proteins encoded by viruses and parasite proteins
What cells express MHC I molecules?
almost every cell in the body
What do proteasomes constantly chew up?
cellular protein (normally deal with defective proteins)
What are peptides?
protein fragments
T/F: Some peptides are brought to the endoplasmic reticulum where they are attached to MHC II molecules.
False; they brought here to attach to MHC I molecules
Where is the peptide-MHC I complex transported?
to the cell surface
What are the specific transport proteins for MHC I molecules named?
TAP 1 and TAP 2
T/F: most peptides are broken down into individual amino acids and excreted as wastes.
False: they are broken down but for the purpose of reuse
How many MHC I genes are there?
6; 3 from mom, 3 from dad
What are the three main gene variants for MHC I?
HLA-A, HLA-B, and HLA-C
T/F: MHC I molecules have an ability to bind many different kinds of peptides.
True
How long are most peptides that bind to MHC I molecules?
8-11 amino acids long
T/F: peptides bound to MHC I molecules are anchored at only one end.
False; they are anchored at both ends
What cells have the responsibility of inspecting peptides displayed by MHC I molecules as self or non-self?
Killer T cells
What are CTLs?
cytotoxic lymphocytes (killer T cells)
What kind of cells eat extracellular proteins?
Antigen Presenting cells (APCs)
Where are MHC II molecules made?
cytosol
Where are MHC II molecules injected after being made?
endoplasmic reticulum
What special protein protects the binding are of the MHC II molecule?
Invariant Chain Protein
What is released into an endosome?
MHC II complex
What is fused with the endosome (with MHC II)?
the phagosome (with extracellular protein)
What breaks down the extracellular protein with the endosome producing peptides?
enzymes
During Antigen Presentation by MHC II, where is the invariant chain protein broken down by enzymes?
within the endosome
T/F: during antigen presenting, the MHC II complex is preserved throughout the process.
True
What are the three types of antigen presenting cells?
Activated dendritic cells, activated macrophages, and activated B cells
T/F: all APCs are white blood cells
True
Where are all APCs made?
bone marrow
T/F: some APCs can function without being activated first.
false; all APCs must be activated first
While the MHC II molecule is in the ER, what sits in the groove to prevent other proteins from binding?
the invariant chain
What is the job of the invariant chain?
to guide the MHC II through the ER and golgi apparatus to an endosome
T/F: MHC II molecules are only open on one end.
False; they are open on both ends
How long are most peptides bound to MHC II molecules?
13-25 amino acids
When the peptides are longer than the area where they bind to the MHC molecule they are allowed to hang over the ends. Which class of MHC is this associated with?
MHC II
When the peptides are longer than the area where they bind to the MHC molecule they are allowed to bulge out. Which class of MHC is this associated with?
MHC I
What kind of cells can be considered T cell-activating cells?
Antigen Presenting Cells
What cells present the antigen to killer T cells and helper T cells?
APCs
What is required for T cell activation?
high levels of MHCs
What cells provide the co-stimulatory molecules required for T cell activation?
APCs
What type of APCs initiate the immune response by activating virgin T cells?
Activated dendritic cells
Where are Sentinel cells located?
beneath epithelial cells
What are naive or virgin lymphocytes?
B or T cells which have never been activated?
What are experienced lymphocytes?
B or T cells which have been activated
T/F: in normal tissue dendritic cells can take in four times their volume of extracellular fluid per hour.
True
T/F: dendritic cells are constantly taking in and spitting out (constantly tasting) extracellular fluid.
True
What is a co-stimulator of dendritic cells?
B7
T/F: Dendritic cells are considered very good antigen presenting cells.
False, they are not very good APCs
What signals activate dendritic cells?
chemical signals from cells engage in battle and recognition of common molecular patterns
What are most pattern recognition receptors?
Toll-like receptors (TLRs)
How many TLRs have been discovered so far?
11
After activated, how long do activated dendritic cells stay in the tissue?
about 6 hours
How long do activated dendritic cells live in lymph nodes?
about a week
If an activated dendritic cell is infected with a virus at the battle ground, where will it be displayed?
on MHC I
T/F: Activated Dendritic cells have an increased expression of B7 co-stimulatory proteins
True
Prior to leaving the battle ground, what do activated dendritc cells make that attract monocytes into the area?
cytokines
After cytokines attract monocytes into the area, what do the monocytes become?
dendritic cells
After sentinel cells sample antigens in tissues, where do they take the samples?
lymph node
Where do activated dendritic cells present the antigen?
to virgin T cells
T/F: Activated Dendritic cells are long lived.
False, they are short lived.
T/F: Activated dendritic cells kill invaders.
False, they get others to do the killing.
What are considered the garbage collectors?
Activated Macrophages
What cells re-stimulate activated T-cells?
Activated Macrophages
T/F: Activated macrophages are considered ferocious killers
True
T/F: experienced T cells only need to stimulated once.
False; experienced T cells nee continual re-stimulation
What cells activate virgin Tcells?
Activated dendritic cells
T/F: Virgin B cells make little MHC II and little B7.
True
T/F: Virgin B cells are used as APC at the beginning of a battle.
False
What activated B cells?
meeting their cognate antigen
T/F: Experience Activate B cells are able to present antigens for helper T cells and concentrate antigen for presentation.
True
How long does it take a B cell to capture the antigen and present it on the cell surface on an MHC II complex?
30 minutes
Do B cell receptors have a high or low affinity for their anitgen?
very high
T/F: Activated B cells have 100-10,000 fold ability to activate T cells over other APCs.
True
Which MHC displays what is happening outside the cell?
MHC II
When do professional phagocytes eat the invader?
if the invader is outside the cell
If the invader gets inside the cell, which MHC shows CTLs what’s going on?
MHC I
