part 7 Flashcards
what does HLA stand for
human leukocyte antigen
which chromosome is MHC genes located on
6
how many genes encode for the alpha region of MHC I
3
which genes encode for alpha region MHC I
HLA A, B, and C
what genes encode for alpha and beta chains of MHC II
HLA-DR, -DP, and -DQ encodes for MHC II alpha and beta chains.
DRa, DRb, DPa, DPb, DQa, DQb.
There is a subgroup of humans that have -DRb2.
Depending on the person, there can be 3-4 MHC II pairs
what properties do MHCs have genetically
polygenic and polymorphic
what is polygenic
many genes
what is polymorphic
many alleles/forms
what operon is similar to MHC operon
lac
what turns on the MHC operon
cytokines
what does IFN turn on
transcription factors like CIITA
what does CIITA do
CIITA protein coordinates various proteins to turn on MHC class II gene transcription and allow the production of MHC class II proteins`
since there are many combinations/alleles of MHC, why is this important
for tissue/MHC matching
what kind of dominance do MHC genes have
codominance
what does codominance allow for in MHC
creates diversity
what is always expressed
Genes are always expressed, alleles are what is specifically expressed.
is polygeny or polymorphy more important
polygeny
what is the first step of polymorphism development
Ancestral MHC gene undergoes gene duplication and divergence
second step of polymorphism development
multiple MHC genes are created
third step of polymorphism development
gene conversion between misaligned chromosomes during meiosis
what is gene conversion
gene A fragment does not swap with A, but with B
fourth step of polymorphism development
chromosomes separate during meiosis
what is alloreactivity
MHC portions are recognized in foreign tissue
what happens if the wrong MHC is transplanted
alloreactivity
1-10% of T cells being activated (very harmful)
shock and rejection
