MHC Flashcards
What is the main function of T- cells?
protect body against intracellular pathogens + to activate macrophages and B cells
True or False: T cells require activation before functioning as effector cells
TRUE
How are T cells activated?
through APCs like:
- Dendritic cells
- Macrophages
- B cells
How do T cells and APCs interact and become activated?
TCRs on T cells bind to proteins on APCs called MHC molecules
What were MHC’s discovered as?
locus of genes responsible for graft rejection
What are the 2 possible outcomes to a skin graft from 1 animal to another?
- the graft will survive and function
- the graft will be rejected (recognized as foreign by MHC)
When will grafts in animals survive? when will they be rejected?
grafts exchanged between INBRED animals survive
grafts exchanged between OUTBRED WILL NOTTTT- rejected
What controls graft rejection or survival?
MHC molecules!
MHC class 1
has receptors for ENDOgenous antigens found on most NUCLEATED cells
MHC class 2
has receptors for EXOgenous antigens found ONLY on APCs
MHC class 3
a mixed group of PROTEINS
including complement components of innate immunity
does not participate in antigen presentation!!
Which MHC class is highly polymorphic?
MHC class 1 (1a, 1b, 1c) are polymorphic
some MHC class II are polymorphic but not all
MHC class 1d
less polymorphic than 1a, 1b, 1c
located outside the MHC, on a dif chromosome
How many MHC class 1a in…
Mice:
Rats:
Humans:
Dogs:
Cattle:
Pigs:
Mice: 30
Rats: 60
Humans: 20
Cattle: 14
Pigs: 11
** NOT ALL ARE FUNCTIONAL
Which MHC class 1a are functional in humans?
A, B and C are functional
the rest are PSEUDOGENES
What does a complete MHC class 2 region contain?
Which ones are found in primates?
3 paired loci
In primates: DPA, DPB, DQA, DQB, DRA, DRB
the A and B are alpha and beta chains
** some are polymorphic
Where were MHC molecules originally found?
on WBCs
What is the MHC of mice called? Rats?
Mice: H-2
Rats: RT1
How are MHC genes expressed?
CO-DOMINANTLY
Each individual has ______ MHC I genes
6
A, B, and C
6 dif class I antigens
When MHC class genes give more diversity?
MHC class II
because different alpha and beta chains may pair to give distinct products
Within a family, what are the chances that 2 of the offspring might share the same MHC type?
1 and 4 chances between siblings
What is a haplotype?
a set of MHC alleles present on a chromosome
Where are MHC I NOT found?
NOT FOUND on RBCs, gametes, neurons, or trophoblast
Which MHC class presents PEPTIDE antigens to CD8+ T lymphocytes
MHC I presents to peptide antigens to CD8+ T cells (cytotoxic t cells)
MHC II molecules present to?
CD4+ T lymphocytes (T helper cells)
What is required for stable expression of MHC class I?
3 things:
- alpha cain (a1, a2, a3)
- B2 microglobulin
- a bound peptide
What makes up the antigen binding groove in MHC 1 molecules?
the extracellular domain makes up the antigen binding groove
What is the most variable part of the MHC class I molecule?
the antigen binding groove
Where do CD8+ T cells bind to on MHC1 molecules?
binds to the non variable a3 domain
What peptides do MHC I molecules accommodate?
peptides of 8-10 AA
What makes up the peptide binding groove in MHC II?
alpha 1 and beta 1 and parts of there appropriate chains
