Antigen Capture and Presentation Flashcards
where are antigens transported from and to
transported from tissue/mucosa to lymphoid organs
when antigens are transported to the lymphoid organs, what occurs
recognition by T cells
what resides in tissues and captures microbes and antigens
dendritic cells
how are cell-free antigens drained
via lymphatic vessels or enter blood stream
which type of DC are the majority
classical DC
where do classical DC (cDC) reside in the lymph node
T cell zone
what do immature DC do
capture and process antigen
how are DC activated
PRR
where do DC migrate to after they’re activated and how do they migrate
LN via chemokine gradient
what is upregulated during DC migration
chemokine receptors (CCR7) and costimulatory molecules
what do mature DC do
present protein antigens to T cells
what do T cells recognize on APCs
they recognize peptide antigens displayed by MHC molecules on the APC
where is the peptide located within the MHC
the pocket
what are the Human MHC proteins called
human leukocyte antigens (HLA)
T/F the genes are not polymophic
F. they are highly polymorphic
what are the two susceptibility factors for periodontitis
HLA-A9 and HLA-B15
T/F in both MHC I and MHC II the peptide binding cleft is located at the amino terminal
True
describe the chains of MHC I
one alpha chain, composed of a1, a2, and a3
what is variable and invariable in MHC I
a1 and a2 are variable, a3 is invariant
how many AA are in a MHC I
8-9 AA peptide
what is the a chain associated with in MHC I
beta2-microglobulin
describe the chains of MHC II
one alpha chain, composed of a1 and a2 and one beta chain composed of B1 and B2.
the groove accommodates how many AAs in MHC II
10-30 AA peptide
where is the variability in the MHC II
variability in a1 and B1, invariable in a2 and B2
CD8 T cells only recognize peptide presented by which MHC
MHC class 1
what binds to CD8 T cells
a3 (invariant portion of alpha chain) binds CD8 on CD8 T cell
where do peptides bind in the cleft
floor of the cleft
where does TCR bind in the cleft
side and top of cleft
CD4 T cells only recognize peptides presented by which MHC
MCH II
what binds to CD4 on CD4 T cells
B2 (invariant portion of beta chain) on MCH II
what does MHC polymorphism ensure
that a population can deal with microbe diversity
how many different kinds of MHC class I
6
how many different kinds of MHC class II
6-8
what is MHC II expressed on and what is it induced by
expressed on APC and induced by IFNy
what is MHC I expressed on
all nucleated cells (all cells but RBCs)
T/F one APC cannot display multiple peptides
F. One APC can display multiple peptides
what does loading of peptides do during MHC assembly
stabilized expression of MHC on cell surface
how long can binding last
up to days to maximize interaction with T cells
how are extracellular proteins (tumor, bacteria) processed
processed in endosome/lysosome and peptides displayed on MHC class II to CD4 cells
what are the three steps of processing extracellular proteins
- antigen INTERNALIZATION
- antigen DEGRADATION in lysosome
- antigen (peptide) ASSOCIATION with class II molecules in endosome
how are cytosolic proteins processed
viruses & bacteria that escape phagosome are processed by proteasome and ER and peptides displayed on MHC class 1 to CD8 cells
what are the 3 steps of processing cytosolic proteins
- antigen DEGRADATION by proteasome
- peptide TRANSPORT via TAP in ER
- antigen (peptide) ASSOCIATION with class I molecules
MHC II presents antigens to:
helper T cells
MHC I presents antigens to:
cytotoxic T lymphocytes
