-
T/F: All nucleated cells can present Antigen (peptides) to T-cells?
T: but, only APC can activate the T-cell through presentation
-
How and where do antigens come into contact with T-cells?
- Afferent lymphatics to Lymph Nodes.
- Carried by Dendritic APC cells
-
T/F: each MHC molecule is specific for one protein to be presented?
False, as long as the protein peptide fits in the cleft it can be presented to T-cells
-
What is the diff b/t histocompatible/incompatible MHC?
- During transplantation, if the MHC molecules from donors do not match = histoincompatible = rejection
- If MHC from donor and patient match = histocompatible = acceptance
-
What are the two steps in attaching peptides to MHC molecules?
- 1) Process: protein degraded into peptides
- 2) Present: Peptide binds to MHC and is presented
-
What MHC molecule is produced by the Cytosolic and Endocytic pathways?
- Cytosolic: MHC I, endogenous
- Endocytic: MHC II, exogenous
-
Describe the Cytosolic MHC I Pathway?
- 1) phagocytose
- 2) Ubiquitinate for proteosome
- 3) pass protein through proteosome
- 4) insert peptides into RER via TAP proteins
- 5) Bind peptide to MHC and transfer from RER - Golgi - vesicles - exocytosis
-
Why is TAP deficiency problematic?
TAP helps bring peptides into the RER so they can be prepared to interact with Tc cells
A patient deficient in TAP cannot attack intracellular microbes (viruses) or tumors and will have lots of immunity problems
-
Describe the endocytic MHC II pathway?
- Phagocytose protein
- breakdown in lysosome
- prepare MHCII in RER + invariant chain
- transport MHCII + invariant chain to endosome
- Release Invariant chain, leaving behind CLIP
- Insert DM to release CLIP and to help with peptide-MHCII rxn
- release through exocytosis to TH cells
-
What is the function of the invariant chain in the endocytic MHCII pathway?
inhibit binding of MHC I peptides since MHC I and MHC II are both made in the RER
-
Can exogenous peptides be presented to MHCI molecules?
Yes, but just during special viral cases when Dendritic cells come in contact with viruses
|
|
