Antigen processing and presentation of foreign antigens on MHC Class II Flashcards
What is MHC?
generic term to describe region of the genome found to control high or low immune responder status to specific antigens
What is the differene in strcture of class I and class II MH/C
class II is composed of an alpha and beta chain heterodimer whereas MHC I is composed a single heavy chain plus beta-2microglobulin
What cells can be induced to express class II MHC?
endothelial cells, mast cells, astrocytes
what cells constitutively express MHC-II?
dendritic cells, monocytes, macrophages, B cells
What controls induction of class II MHC?
transcription factors which bind to upstream promoter sequences
what is the function of HLA-DM?
catalyses peptide binding to MHC class II molecules
What is the function of MHC class II transactivator?
positive transcriptional co-activator of MHC-II genes
What is the function of polygeny?
presene of several different related genes with similar functions ensure that each individual produces a number of different MHC molecules
Which MHC protein is monomorphic?
DR alpha chain
Which type of class II molecule is expressed most?
HLA-DR
What are HLA-DM and HLA-DO?
intracellular class II moelcules with functions in peptide loading- remove the li derived CLIP peptide and load exogenous peptide
What happens to MHC class II molecules after biosynthesis?
stabilised with a peptide- CLIP dervied from a protein:invariant chain (li)
What is often found in the HLA-DR cluster?
an extra beta-chain gene whose product can pair with the DR alpha gene
What does the extra DR beta chain mean?
there are 4 types of MHC-II molecules from 3 sets of genes
Why are some HLA class II associated with autoimmunity?
polymorphic diferences in the peptide-binding groove impact the generation of disease through autoreactive CD4 cells
