B2 antigen processing and presentation Flashcards
antigen processing and presentation
what does the t cell recognise
antigen
phagocytosis generates lots of short peptides from pathogen associated proteins and this is what t cells recognise
how is antigen recognised
peptides presented to TCR in context of major histocompatibility complex (MHC)
- 2 forms
MHC I CD8 t cells
MHC II CD4 t cells
how antibodies and TCR recognise antigens
-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
in terms of MHC how is antigen recognised
-different pathways for antigen presentation by MHC
-MHC I for intracellular antigens CD8 T cells
-MHC II for extracellular antigens CD4 T cells
how T cells orchestrate cell mediated immunity and regulate B cell responses to most antigens
-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
how is antigen recognised in regards to haplotypes
-diversity in MHC haplotypes within pop
-increases range of peptides presented to immune system within species
-reduces chance of pathogen invading immune system
what affects antigen recognition and how
MHC polymorphism affects antigen recognition by t calls by influencing both peptide binding and contacts between TCR and MHC mol