B2 antigen processing and presentation

Question 1

what does the t cell recognise

Answer 1

antigen
phagocytosis generates lots of short peptides from pathogen associated proteins and this is what t cells recognise

Question 2

how is antigen recognised

Answer 2

peptides presented to TCR in context of major histocompatibility complex (MHC)
- 2 forms
MHC I CD8 t cells
MHC II CD4 t cells

Question 3

how antibodies and TCR recognise antigens

Answer 3

-the epitopes recognised by t cell receptors are often buried
-antigen must first be broken down into peptide fragments
-the epitope peptide binds to a self molecule, an MHC molecule
– the TCR binds to a complex of MHC mol and epitope peptide

Question 4

in terms of MHC how is antigen recognised

Answer 4

-different pathways for antigen presentation by MHC
-MHC I for intracellular antigens CD8 T cells
-MHC II for extracellular antigens CD4 T cells

Question 5

how T cells orchestrate cell mediated immunity and regulate B cell responses to most antigens

Answer 5

-virus infects cell
-viral proteins synthesised in cytosol
-peptide fragments of viral proteins bound by MHC I in ER
-bound peptides transported by MHC I to cell surface

Question 6

how is antigen recognised in regards to haplotypes

Answer 6

-diversity in MHC haplotypes within pop
-increases range of peptides presented to immune system within species
-reduces chance of pathogen invading immune system

Question 7

what affects antigen recognition and how

Answer 7

MHC polymorphism affects antigen recognition by t calls by influencing both peptide binding and contacts between TCR and MHC mol