L11: T-cell Development Flashcards
1
Q
DN1
A
- has c-kit
- high CD44
2
Q
DN2
A
- γδ or β genes begin rearrangement
- has c-kit
- CD44 decreasing
- CD25 appears
- RAG genes turned on
- CD3 begins
3
Q
DN3
A
- γδ stop here, β- pre α-receptor
- has c-kit but low
- CD44 is low
- CD25 low
- RAG genes up (but off in γδ)
- CD3 present
4
Q
DN4
A
- begin α gene rearrangement
- CD44 and c-kit now gone
- CD25 up
- RAG declines
- CD3 present
5
Q
DP
A
- αβ receptor complete
- CD44, c-kit, and CD25 gone
- RAG rises
- CD4/CD8 now both present
- CD3 present
6
Q
Positive selection
A
-DP Tcells must bind to an MHC (either I or II) with enough affinity, otherwise they’ll be killed after 3-4 days
7
Q
Negative selection
A
-DP Tcells bind too well to self-antigen presented on MHC, therefore they are eliminated
