Antigen processing and presentation of foreign antigens on MHC Class II Flashcards Preview

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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?



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


What can be used as a tool for counting and puridying peptide specific T cells?

streptavidin-bound HLA class II/peptide tetramers


What are products of individual MHC allels known as?

protein isoforms


what is a sequence motif?

the set of anchor residues (on binding peptides) that allow binding to a given isoform of an MHC molecule


What is an immune response gene defect?

when processing of a protein doesnt generate any peptides that can bind to MHC in an individual which results in individual being unresponsive to that antigen