antigen presentation

Question 1

what cells are antigen presenting

Answer 1

• macrophages
• dendritic
• b cells

Question 2

how is MCHII involved in antigen presentation

Answer 2

1. pathogen is internalised by phagocytosis
2. lysosomes merges with the phagosome to produce a phagolysosome and digest the pathogen
3. a second vesicle containing MCHII fuses with the phagolysosome to pick up peptide fragments
4. MCHII with peptide bound is delivered to the surface for presentation

Question 3

how do co-stimulatory molecules work

Answer 3

• dendritic cells need to express co stimulatory molecule and chemokine receptors to reach the lymph nodes
• B7.1.B7.2 signals that the antigen has come from a pathogen

Question 4

how is B7.1/B7.2 turned on

Answer 4

• when the TLR recognition has sent a signal to the nucleus
• up regulation of the protein

Question 5

cross presentation of antigen

Answer 5

• dendritic cell uses this to see if it is a bacteria or a virus
  1. partially degraded antigen can be pushed from phagolysosome into the cystol to be processed through MHCI
  2. the dendritic cells also have vesicles with MHCI in as well as MHCII - can fuse to phagolysosome to load peptide in MHCI for the surface

Question 6

what is expressed for intracellular infection

Answer 6

• INFa
• INFb
• (makes a co-stimulatory molecule expression)