7. T-lymphocytes Flashcards
T helper cells
- Express CD4+
- Able to recognize MHC2 molecules
- 66% of all T cells
Cytotoxic T cells
- Express CD8+
- Recognizes MHC1
- 33% of all T cells
Negative selection
The T cells that recognizes MHC + self peptides with high affinity dies via apoptosis
Positive selection
Double positive T cells will recognize self MHC1 or 2. Those that recognize MHC1 will loose the CD4+ and become a single positive CD8+ thymocyte
Cytotoxic T lymphocytes
-Can recognize virus infected cells
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CD4+ T cell
- Produces different cytokines after activation
- Produce IFN gamma -> mainly Th1 cells
- Th2: produces IL-4,5. Help B cells to mature into plasma cells
Regulatory T cells
- Produces TGfb and IL35, IL10
- Inhibit the effector T cells
- CD4+ cells that can produce perforins and granzymes
Positive and negative selections happens where?
In the thymus
T cell activation happens where?
In peripheral organs
Two classes of TCR
Alpha and beta chain, or gamma and delta chain
What happens to gamma,delta TC
Migrate to mucosal and cutaneous tissues -> 1st line defense
Molecules in positive costimulation
CD28 on T cell binds to B7 on APC
Molecules in negative costimulation
CTLA4 on T cell binds to B7 on APC
A double negative thymocyte can differentiate further into?
- A double positive thymocyte
- A gamma, delta T cell
- NKT cell
Th1 activates
Macrophages, Tc cells, NK cells
