Cell-Mediated Immunity Flashcards
TCR complex: First signal
TCR binds antigen, CD3/zeta chain generate signal
TCR complex: Second signal
CD28 (T-cell) binds CD80/86 (APC)
TCR complex: Third signal
Cytokines (depends on infection)
What stabilizes the interaction of APC with TCR?
LFA-1 binds ICAM-1
T-cell accessory molecule used for signal transduction by TCR complex
CD3 / zeta chains
Function of CD4 and its ligand
Function: Signal transduction
Ligand: Class II MHC on APCs
Function of CD8 and its ligand
Function: Signal transduction
Ligand: Class I MHC on APCs, Class I target cells
Function of CD28 and its ligand
Function: CO-STIMULATION
Ligand: CD80/86 on APCs
Function of CTLA-4 and its ligand
Function: Signal transduction (negative regulation)
Ligand: CD80/86 on APCs
Function of LFA-1 and its ligand
Function: Adhesion
Ligand: ICAM-1 on APCs and endothelial cells
What secretes IFN-gamma and IL-12 for Th1 induction?
Dendritic cells
What are the three functions of IFN-gamma?
- Stimulates complement and Fc receptor-binding IgG subclasses (activates B cells in the lymph nodes to release IgG)
- Macrophage activation (classical pathway)
- Recruits monocytes
Actions of activated macrophages
- Secretion of TNF, IL-1, IL-12, chemokines
- Increased expression of MHC, CD80/86
- Killing of phagocytosed bacteria
What interaction is required for macrophages to be activated?
CD40L on T-cell binding CD40 on macrophage
What are the functions of the cytokines produced by activated Th1?
TNF alpha –> endothelial cells –> inflammation
IL-2 –> T cell differentiation
IFN-gamma –> macrophage activation –> intracellular pathogens
What are the functions of the cytokines produced by activated Th2?
IL-4 –> IgE –> allergic reactions
IL-5 –> basophils –> helminths
IL-13 –> same as 4
What are the functions of the cytokines produced by activated Th17?
IL-17 / IL-22 –> neutrophils –> extracellular pathogens
Which cytokine is imperative for T cell differentiation/proliferation?
IL-2
Where are T cells activated?
Paracortex of lymph nodes
PALS of spleen
What is cross presentation?
Dendritic cell can phagocytize a cell (usually presented on MHC II), but still present to CD8 cell via MHC I
What granules do CD8 cells release? What are their functions?
Granzyme
Perforin
Perforin perforates the pathogen membrane, then releases granzymes to induce apoptosis
Which cytokine supports proliferation and differentiation of developing lymphocytes in the primary lymphoid tissue?
IL-7
What do macrophages produce to promote Th1 differentiation and inflammation?
TNF-alpha
IL-1
IL-12
Which immune cells are responsible for the formation of a granuloma?
Th1 cells
Macrophages
