IMIN Lec. 5 Flashcards
Where do lymphocytes see APCs
lymph nodes
Where do lymphocytes differentiate
Lymph nodes
Where are APCs found and what do they do?
Activation of T cells, found in sites of microbial entry. They transport antigens to periphery where they can present antigens to T cells
APCs present antigens on
MHC class one and two
What does the MHC locus contain
two sets of polymorphic genes
Polymorphism is
multiple alleles of a gene within a population
How is peptide anchored
side chains bind into cleft.
additional residues are recognized by TCR in membrane
MHC molecules have ____specificity
broad
Any given MHC can present any peptide
with correct anchor residues
Class II is presented to by
Professional APCs
Class I presented to by
All nucleated cells
Class I MHC has which chains?
alpha1 and alpha2->polymorphic residues are located in these domains, affecting peptide binding
alpha3 is invariant and contacts CD8
Transport Associated with Antigen Presentation
drives transport of cytoplasmic proteins into ER
Where does Class I associate with peptides?
in ER leumen
what occurs if there is stable binding?
complex sent to cell surface via Golgi and exocytic vesicles
Class II has which chains
alpha, noncovalently linked to beta
Where does class II bind with microbes? Where does class I interact with intracellular microbes?
cell surface vs. cytoplasm
Where do class I and II interact with peptides?
In ER; when endosomal vesicles can fuse with exocytic vesicles with MHC, and the invariant chain is removed
CD4 T lymph stimulate
B lymph to make antibodies+phagocytes
Properties of MHC
co-dominance and polymorphism
Features of peptide binding to MHC
each T cell responds to a single peptide bound to MHC
- broad
- slow off rate
- stable exp. needs peptide for T cell recognition
- only restricted to peptides
What provides 2nd signal for T lymph differentiation+T cell activation
costimulators and cytokines
