Lecture 12: T-Cell Development and MHC Flashcards
γδ T cells never express ________.
CD4 or CD8
Outline the T-Cell selection process:
Positive:
- TCR engages in a low-affinity interaction with self MHC = Maturation
Lack of Positive:
- TCR does not interact with self MHC at all = Apoptosis
Negative:
- TCR engages in a high-affinity interaction with self MHC = Apoptosis
Unlike BCR and antibodies, which recognise their cognate antigens in their ___________, TCR can only recognize their cognate antigen as _________________.
Native form
Short peptides bound to MHC
What do Th1 cells do?
- Activate MO to stimulate Microbicidal activity
- Induce class switching of activated B-cells
What do Th2 cells do?
- Induce class switching of activated B-cells
Describe the structure of an Antibody:
- Fab fragment is an S-S linked heterodimer, each chain has an IgC and IgV domain
- Ag binding site is at the juxtaposition of the V regions
Describe the structure of the TCR:
- S-S linked heterodimer, each chain has an IgC-like and IgV-like domain
- Ag binding site is the juxtaposition of the Vα and Vβ regions
In the V region of each TCR chain there are ______________ or ______________________. The primary Ag recognition domain is ______.
3 Hypervariable
Complementarity Determining Regions (CDRs)
CDR3
The TCRα locus is on chromosome ___ and consists of ___________.
14
70-80 V, 61 J, and 1 C regions
The TCRα locus is on chromosome ___ and consists of ___________.
7
52 V, 1 D, 6-7 J and 1 C regions
MHC class 1 presents _________ or __________ Ag from ___________ pathogens.
Intrinsic or Endogenous
Intracellular
MHC class 2 presents _________ or __________ Ag from ___________ pathogens.
Extrinsic
Exogenous
Extracellular
MHC class one is expressed on _____________________________
All uncleared cells, especially highly expressed on HSC
MHC class 2 can be expressed on cells other than ______ in response to ______
APC
IFN-γ
Human MHC locus is on chromosome ___
6
The MHC that a cell expresses determines what _______________ and to which _________ they present to
Peptide antigen
T-Cell
What are the key features of MHC class 1?
- heavy chain α bound to β2 micro globulin
- α1 and α2 domains form the antigen binding site
- binds peptides 8-10aa long, ends are bound
What are the key features of MHC class 2?
- heterodimers of α and β chains
- No β2 microglobulin
- binds peptides that are >13aa long, ends not bound
The ______ region on MHC class 1 binds to CD8
α3
The ______ region on MHC class 2 binds to CD4
β2
Class 1 MHC has 6 _________________ which convey specificity
Binding pockets
What is the function of CD4 and CD8?
Their binding to the membrane-proximal domains on MHC is required to produce an effective response
What are super antigens?
Molecules produced by many pathogens that are recognised by T-Cells without being processed into peptides and presented on MHC
Super antigens bind to _____________________________
Outside of MHC class 2
