MHC T cells Flashcards
What makes up an MHC haplotype
Combination of MHC 1, 2, 3 on one chromosome
What does MHC 1 present on
all nucleated cells
proteins inside of cell sampled
What does MHC 2 present on
antigen presenting cells
Proteins sampled outside of cell
activates adaptive immune system
What is heterozygous advantage
Each person is able to express alleles from both parents
Can express all of the genes simultaneously
How are MHC genes expressed with heterozygous advantage
co-dominantly expressed
What is polygeny
expression of several different but related genes with similar functions
What does MHC present
Many different peptides
What does the TCR recognize
the peptide and part of the MHC
Which is larger MHC 1 or 2
MHC 2
What is MHC 3
Not a receptor or presenting molecule
What must the T-cell recognize for the signal to work
Both the MHC receptor and the antigen
What is a super-antigen
Antigen not presented by MHC
Crosslinks nonspecific TCR and MHC
Can activate up to 20% of bodies T cells
Characteristics of super-antigen response
Large and ineffective
What are the two basic structures of TCR
gamma/delta
Alpha/beta
What are the characteristics of Gamma/delta TCR
Recognizes native antigens
No MHC
bridges gap of innate and adaptive immunity
What are some characteristics of alpha/beta TCR
Recognizes foreign peptide in context of MHC
Signaling to cell nucleus by CD3
Requires CD8 or CD4
What are some characteristics of CD4 and CD8
TCR co-receptor
amplifies the signal of the TCR MHC-peptide interaction
What does CD4 bind to
MHC 2
What does CD8 bind to
MHC1
What do CD4 and CD8 do to the sensitivity of T cells to peptide antigen
increase sensitivity
What do cellular adhesion molecules(CAM) do
Keep APC and T cells close
What is immunologic snapse
Area of adhesion
Localized area of interaction
Many TCR complexes
What is happens during the second signal
Activation of naive t cells requires 2 independent signals delivered by the same APC
Protects against activation by self MHC
What initiates the second signal on APC
B7 activates second signal through CD28
When is B7 expressed
When APC is activated
What happens if T cell gets first signal but not the second
Cell turns off
Doesn’t want to react with self
What happens if the naive T cell recognizes the antigen, MHC, signal 1 and signal 2
Cell replication
Cytokine synthesis
What is tolerance
when T-cell is turned off
What happens when CD8 T cell becomes primed
after CD8 receives both signals from APC, only the first signal is needed for recognition and killing
What’s CTLA4
CD28 receptor expressed on CD4 T cells
Has higher affinity than CD28
Signals T cell to turn off
What stimulates CTLA production
Activation of T cells
What does Alpha/beta T cells become
CD4 or CD8
What do CD4 cells become
Helper 1 and Helper 2
What do CD8 T-cells become
Cytotoxic or regulatory
What does Th1 produce
IL-2
IFN-Gamma
What does TH2 produce
IL-4
IL-5
IL-10
What’s a haplotype
Set of linked MHC alleles found on the same chromosome
Genetic potential of an individual
How are T-cells MHC restricted
Because they must see antigen in the context of MHC
