MHC Flashcards
Specialized glycoproteins coded for by genes located in a gene cluster
- the Major Histocompatability Complex (MHC)
Determine which MHC molecules an individual animal can produce
- MHC genes
Determine which antigens can be presented to the cells of the immune system
- MHC molecules
MHC restriction
- antigens can only trigger an immune response if they are bound to a self-MHC molecule
______ can only recognize antigens in the context of self-MHC molecules
- T-cells
What kind of immune response is most helpful to deal with extracellular pathogens?
- humoral immune response
- > antibodies neutralize extracellular pathogens
What kind of immune response is most helpful to deal with intracellular pathogens?
- cell mediated immune response
- > kill infected/tumor cells
How does an exogenous antigen get into the endogenous pathway?
- cross-presentation (cross-priming)
Cross-presentation (cross-priming)
- Exogenous antigens may enter the endogenous antigen pathway in an antigen presenting cell (APC) and thus be presented via MHC-1 to CTLs (cytotoxic T-lymphocytes)
- > phagosomal leak
What response is needed in order to kill virally-infected cells?
- a CTL (CMI) response
How can an endogenous viral antigen end up in the exogenous pathway?
- in APCs via phagocytosis of ingected cells
How is it that in all acquired immune responses to a pathogen, we will see both CMI and humoral immune responses?
- via cross presentation (exogenous on MHC-I) and phagocytosis of infected cells (endogenous on MHC-II)
Alleles code for different amino acid sequences for the ______ of the MHC molecule
- peptide binding groove
- > structure of the MHC binding groove determines what antigens it can bind and present
What type of specificity do MHC molecules have?
- Broad specificity (promiscuous)
- > a given MHC molecule can present ONE peptide at a time, but can bind several different peptides
What type of specificity do TCR (T-cell receptors) molecules have?
- Unique specificity
- > can only interact with self MHC presenting one specific peptide
MHC genes determine disease susceptibility when the _____ immune responses are essential
- acquired
In humans almost all autoimmune diseases are linked to certain ______
- MHC alleles (genes)
Is it an evolutionary advantage or disadvantage to be heterozygous?
- advantage because more heterozygous MHC = greater diversity of bound peptides
- > if lack of MHC diversity aka homozygous populations, they are less likely to have individuals who can respond to a novel pathogen
Do MHC genotypes cause disease?
- NO, they are linked to risk only
