Antigen presentation Flashcards
Which chromosome encodes MHC proteins?
Chromosome 6
What are MHC proteins called in humans?
HLA (huma leukocyte antigens) proteins
What is the MHC haplotype?
the total set of MHC genes (D region genes and A, B, and C genes) on each chromosome.
What is MHC polygenic
Because an individual inherits one haplotype from each parent, and is thus comprised of many different genes within an individual
What makes MHC gene expression polymorphic?
Multiple variants of each gene exist in the population as a whole
True or false: MHC genes are by far the most polymorphic genes known in humans.
True
What is the system that distinguishes different HLA protiens within a given gene family?
The number tagged onto the end ot the HLA type (example: HLA-A3 or HLA-A15).
What does it mead to say that MHC genes codominant?
alleles on both chromosomes will be expressed simultaneously
Which region on DNA encodes for class II MHC proteins?
D regions
Which region on DNA codes for class I MHC proteins?
A, B, and C genes
How many MHC genes do we receive from each parent?
3 from each parent
How many MHC genes are expressed by an individual?
6 total, but may be more higher because some class II MHC α and β proteins (which compose each class II MHC protein) can pair up with other class II MHC α and β proteins to produce new α/β chain combinations
What three characteristics of MHC genes virtually guarantees that no two individuals (save twins or siblings) will have the same MHC genes?
The polygenic, polymorphic and codominant characteristics
What is the function of MHC proteins?
Present antigens to T cells
True or false: T cells can generate a response without the help of an MHC cell
False (“need to be spoon-fed”)
What sort of bond exists between peptides and MHC proteins on the cell surface?
Non-covalent
True or false: there is no bonding between MHC cells and T cells, only the antigen connect them
False
What is the purpose of T cells not being able to bind to antigen directly?
Localizes to anatomic site of antigen presentation
True of false: MHC cells can bind to antigens that are not proteins
False
What disease is associated with narcolepsy?
HLA-DR2
What disease is associated with HLA-B27?
Ankylosing spondylitis
What is the immune response theory of the HLA gene association with diseases?
Some individuals are unresponsive to certain pathogens because that antigen cannot be bound to that particular individual’s HLA proteins.
What is the altered self hypothesis of the HLA gene association with diseases?
The disease agent alters molecules of an individual’s body such that the immune system now recognizes it as foreign when it binds to certain HLA proteins.
Why might the associated of HLA genes and various diseases have no causative connection to one another?
May just be in close proximity to diseased allele, and thus usually inherited together
What are the two clinical uses of MHC typing?
Organ transplant
Paternity testing
Why is MHC matching important in organ transplant?
of organs between individuals may be rejected since a non-self MHC protein will be recognized as foreign.
Can paternity tests done via HLA haplotypes 100% rule out a father? Can they 100% rule in?
Can rule out 100% but cannot rule in 100%
Which class of MHC proteins are expressed on nearly all nucleated cells? Which cell type does not express it?
Type I
Corneal epithelium and RBCs
Why does Plasmodium, the causative agent in malaria, go undetected by T cells?
RBCs do not have MHC class I
What are the two chains in class I MHC proteins? Which one forms the binding site for antigens?
Alpha and beta, with alpha forming the binding site
What are the four regions of class I MHC proteins?
- peptide-binding region
- immunoglobulin-like region
- transmembrane region 4. cytoplasmic region.
The beta portion of the class I MHC protein does not bind to antigen. What, then, is its function?
The beta2 microglobulin is required to keep the proper conformation and cellular expression of the beta chain.