Lec 45: Adaptive Immunity II (NSD) Flashcards
What are the two subsets of helper T cells?
Th1 and Th2
What type of cells to Th1 cells attach to?
Dendritic cells and Macrophages
What receptors do Th1 cells directly bind to?
MHC II-antigen complexes; CD40
What are the primary cytokines secreted by TH1 cells?
Interferon-gamma (IFN-gamma); Interleukin-2 (IL-2)
What does interferon gamma do?
- Activates “resting” macrophages
2. Inhibits Th2 activity
What major cytokine is produced by APCs when they come in contact with intracellular pathogens?
Interleukin-12 (IL-12)
What effect does IL-12 have on T cells and natural killer (NK) cells?
- CD8+ and NK cells: More IFN-gamma secretion and increased cytolytic activity
- Naive CD4 cells –> Th1 cells –> increased IFN-gamma secretion
What type of cells to Th2 cells attach to?
B cell presenting specific antigen
What receptors do Th2 cells directly bind to?
MHC II-antigen complexes; CD40
What are the primary cytokines secreted by TH2 cells?
IL-4; IL-5
What effect do IL-4 and IL-5 have on their target cells and on Th1 cells?
- B-cell differentiation and antibody production
2. Inhibition of Th1 cells
What is the primary function of CD8 cells?
Induce apoptosis in cells infected with viruses/intracellular pathogens
What happens to a virus once inside a dendritic cell?
- Viral proteins are produced in the cytosol on the cell
- Viral proteins are degraded
- Degraded proteins are transported from cytosol to ER
- Peptide-MHC class 1 complexes formed in ER
- Complexes move to cell surface
- Complexes are recognized by CD8 cytolytic lymphocytes
What are the differences in the 3 major pathways for activation in naive CD8 (CTL) cells?
- Without help from CD4 cells
1a. CTL binds to MHC I-antigen complex and B7 on virus-infected cell
1b. IL-2 is produced by CTL and drives its own proliferation and differentiation
2+3 With help from CD4 cells
- Nearby CD4 T cell helps CTL binding by inducing B7 expression on surface of APC
- Nearby CD4 T cell helps CTL binding by releasing IL-2
What types of cells can naive CD8 cells differentiate into?
Effector T cells or memory T cells