IAH revision session - adaptive immunity MHC Flashcards
NAme 3 types of infection (in terms of where int he cell they infect)
Cytosolic
Intravesicular (phagocytosed)
Extracellular pathogens and toxins
What type of pathogens lead to cytosolic infections?
Viruses
What peptide to cytosolic pathogens bind to?
MHC class I
What peptide to intravesicular and extracellular pathogens bind to?
MHC class II
How are extracellular pathogens and toxins presented?
Taken up by B cells are presented via MHC II on the surface of the B cell
Effect of presenting cytosolic pathogen antigens on MHC I
Cell death
Effect of presenting intravesicular pathogens on macrophages via MHC II
Activate CD4 cells which activate macrophages and kills bacteria
Effect of presenting extracellular pathogen on B cells via MHC class II
Activation of B cells to secrete Ig to eliminate extracellular bacteria and toxins
How is MHC adapted to be hard to overcome?
Polygenic and polymorphic
Where are the majority of polymorphisms on MHC alleles?
On the antigen binding section
What is the purpose of polymorphisms?
Population has lots of ways of fighting infection = drive evolution via the population not the individual
What pathway processes cytosolic pathogens to MHC I?
Intracellular
What is a key component to distinguish between intracellular/cytosolic pathway and extracellular pathway?
Intracellular goes via the ER
Why is herpes simplex virus contained in one lesion?
Cytosolic infection = only a few cells = easily contained by CD8 and CD4 help
Why are mycobacterium hard to present on surface by MHC?
Very resistant to proteolysis in the endocytotic pathway so cannot break down and then not bind to MHC II
