Flashcards in Antigen presentation and the MHC Deck (35):
Location of macrophages
Blood, liver, spleen
location of dendritic cell
Skin, lymphoid tissues
Location of B cells
Lymphoid tissues, infection sites
Macrophages in the different parts of the body
Microglia in the brain, Kupffer cells in the liver
Langerhans cells, which line the junction of the dermis and epidermis
How do skin APCs help the immune response?
They travel to the paracortex and present to the T cells there
Plasmacytoid dendritic cells
Produce large quantities of interferon in response to viral infections
Conventional dendritic cells
Undergo a maturation process
From what are antigenic peptides usually derived on an MHC I molecule?
Viruses that have taken over the cell
How are invaded viruses made into antigens?
Proteosomes in the cell degrade them and put them on the MHC (subunits LMP2 and LMP7)
Transport of peptides to the MHC
Transported by TAP-1 and -2
ER antigen chaperones
Erp57, calnexin, calreticulin
What is the purpose of ER chaperone proteins?
Blocks the MHC from being bound by anything other than its antigen
Removes the chaperone proteins and allows the binding of the antigen to MHC in the endoplasmic reticulum
After the antigen is attached in the ER, what happens?
The antigen complex moves through the golgi body, is put into a vesicle, and transported to the cell surface
From what are MHC class II antigens derived?
The products of degradation from phagocytosed substances
What is the associated protein with MHCII?
How is Ii removed from the complex?
What is left in Ii's spot after acidification?
What loads/unloads CLIP from the complex?
What is displayed in the MHC complexes when there is no foreign antigen?
Class I: self antigen
Class II: CLIP
Induce antibody synthesis
Also known as CD80 or CD86; co-stimulatory molecule on APCs
What are the two signals necessary for activation of T cells?
Binding to the MHC and also the interaction of B7 with CD28
Why would an APC not express B7?
When they take up antigens that are not microbial, they don't always express B7
What happens when B7 is not expressed?
When T cells recognize the MHC on an APC, they stimulate the APC to express CD40, which binds to the CD40L on the T cell and takes the place of the B7/CD28 interaction
What is the interaction between B7 and CD28?
CD28 cleaves B7 and then induces T cell proliferation and differentiation
What stimulates the B cell to make B7?
Presence of the antigen on the MHC
What happens after MHC-peptide engagement?
TCR initiates a phosphorylation cascade that triggers a lot of branching pathways
Time course of MHC-peptide engagement
If bound for a short period of time, killer T execution will be activated; however, complex functions like T cell proliferation take a connection that lasts minutes-hours
Mature immunological synapse
Specific pattern of receptor recognition with a central cluster of TCRs surrounded by a ring of adhesion molecules
Enriched with adhesion molecules like LFA-1 and ICAM-1 that promote efficient TCR-MCH-peptide interaction and lead to a biological response
Location of ICAM-1 and LFA-1
LFA-1: T cell surface
ICAM-1: APC surface