T Cells Flashcards
T cells respond to
Protein antigens : Viruses, Bacteria, Pathogens
Where does T lymphocytes arise from and mature at?
Arise from stem cells in BM
Mature in thymus
T cell maturation steps
1- Haemopoietic stem cells
2-Pre-B and Pre-T cells
3- T cell differentiation in thymus— Negative and Positive selection
4- Maturation In thymus
5- Circulating mature B and T cells
6- Peripheral lymphoid organs
The maturation of lymphocytes from BM stem cells consists of 3 types of processes
1- Proliferation of immature cells
2- Expression of ag receptors
3- Selection of lymphocytes that express useful ag receptors
Steps in the activation of T lymphocytes
Antigen recognition
Activation
Clonal expansion
Differentiation
Activation of macrophages, B cells or Killing of infected target cells, macrophage activation
Which IL is for T-cell non-specific proliferation
IL-2R
The TCR recognizes=?
MHC-associated peptide antigens
CD4 or CD8 co-receptors recognize
MHC molecules
Adhesion molecules strengthen the binding of
T cells to APCs
Receptors for costimulators recognize
Second signals provided by the APCs
T cell accessory molecules that involved in T cell activation
CD3
Zeta chain
CD4
CD8
CD28
CTLA-4
LFA-1
VLA-4
Function of the CD3 molecule
Ligand of CD3
Signal transduction by TCR complex
No ligand
Zeta chain function
Ligand
Signal transduction by TCR complex
No ligand
CD4 function
Ligand of CD4
Signal transduction
Class 2 MHC — expressed on APCs
CD8 function
Ligand name
Signal transduction
Ligand = Class 1 MHC
