9 - MHC Flashcards
When do T and B cells undergo random recombination?
when they undergo maturation
What do BCRs recognize and bind to?
free (soluble) antigen part of a larger pathogen or toxin
What are the 2 necessary things that TCRs must recognize and bind to?
antigenic (antigen-derived) peptides | MHC molecule that is bound to the antigenic peptide
What does exogenous mean?
extracellular
What does endogenous mean?
intracellular
What are the 3 functions of MHC molecules?
antigen-presenting molecules | form stable complexes with peptide ligands | display antigen on cellular surface for TCR engagement
Which cells express MHC I?
all nucleated cells
Which cells express MHC II?
APCs or cells involved in immune responses
What family are MHC I and II both part of?
Ig (immunoglobulin) superfamily | sticky domain
How long can the peptide be to fit into MHC I?
8-10 amino acids
What 2 polypeptides that make up the MHC I structure?
large transmembrane alpha chain | small beta-2 microglobulin protein for stability
Which polypeptide makes up the peptide binding groove of the MHC I?
alpha chain
What polypeptides make up the MHC II structure?
heterodimeric transmembrane alpha and beta chains
How long can the peptide be to fit into MHC II?
13-18 amino acids
Which T-cells do MHC I molecules present peptides to?
CD8 CTLs
Where are the peptides that bind to MHC I derived from?
endogenous intracellular proteins
Which T-cells do MHC II molecules present peptides to?
CD4 Th cells
Where are the peptides that bind to MHC II derived from?
exogenous extracellular processed antigens
If there are no foreign peptides for MHC I to present, what does MHC I do and why?
will present self-proteins on its surface | this is a way the immune system checks if cells are self and are healthy (not cancerous)
What is the organelle that protein (self or foreign) will be randomly broken down in?
proteosome
What will MHC I do if the cell is infected with an intracellular bacteria or virus or is a tumor cell?
MHC I will load viral, bacterial, or cancer-related protein on its peptide-binding groove and present it on surface | CTLs will be activated if it recognizes the peptide
What are the 3 types of APCs?
B-cells | macrophages | dendritic cells
What is the role of MHC II?
helps direct responses against things that shouldn’t be in our system »_space;> display those peptides to activate Th cells
What are the 4 things that can induce change in MHC expression?
genetic regulatory components | viral interference | cytokine-mediated signaling | steroids
How do genetic regulatory components influence MHC expression to change?
PRR signaling can lead to more expression of MHC molecules | promoters can drive transcription during times of infection due to PRRs
How does viral interference influence MHC expression to change?
viruses shut down MHC I expression because it targets the cells they are in for destruction via NK cell
How does cytokine-mediated signaling influence MHC expression to change?
some cytokines such as TNF and Type-I IFN can upregulate MHC expression
How do steroids influence MHC expression to change?
can upregulate it | steroids cause inflammation
MHC alleles are ____ expressed.
co-dominantly
What is an issue that MHC prompts and why?
presents issues for transplantation because MHC must be compatible
In terms of MHC compatibility, who can Person A donate tissue to or from? (4)
sibling | to offspring | from parent | with self
In terms of MHC compatibility, who can NOT Person A donate tissue to or from? (3)
to parent | from offspring | with partner
What will happen if the donated tissue does not match the recipient’s MHC?
recipient’s immune system will attack and reject donated tissue
What is MHC restriction?
MHC compatibility
