Differentiation and Funciton of CD8+ cells Flashcards
What molecule has a profound effect of inducing naive CD4+ T cells to differentiate into Th1 effector cells?
IL-12
What is responsible for the proliferation and differentiation of CD8+, CTLs, and memory cells?
IL-2. Functions through an autocrine loop.
Name the source and function of IL-15?
Source- activated tissue macrophages and mature DC’s
Function- chemoattractant for T cells, stimulates proliferation of memory CD4+ and CD8+ and naive CD8+ T cells.
Name the two main T cells, their correct marker, approximate percentage in the blood, and whether they are MHC-1 or MHC-2./
1) Helper T Lymphocytes (Th)-CD4, 66% of T cells, MHC class 2
2) Cytotoxic T Lymphocytes (CTLs)- CD8, 33% of T cells, MHC class 1
Describe the process of CD8 T cell activation.
They are activated in the LN by DC’s loaded with Ags exactly as CD4 T cells are. CTLs recognize class 1 MHC associated peptides. Activated CD8 cells proliferate and leave the LN.
What are the ways that a CD4+ T cell can activate CTLs?
1) CTL’s can recognize costimulators and on professional APC’s.
2) CD4+ produce cytokines that stimulate CTL differentiation.
3) CD4+ enhance the ability of APC’s to stimulate CTL differentiation.
Where are granules contained and what are their functions?
Activated CTLs contain numerous granules called lysosomes that contain perforin and granzymes used by the cells to kill other cells.
What are the three main signals of CTLs activation?
1) Naive CD8 recognition of Ags.
2) CD28-CD80 costimulation.
3) CD4+ provide signal in form of cytokines when enhance activation.
What is IL-12 and type 1 IFNs function with respect to CD8 T cells?
stimulate the differentiation of naive CD8+ T cells into effector CTLs. CD8 require IL-12 or type 1 IFN for survival and development of optimal effector functions
Describe the function of IFN-gamma.
Released by Th1 cells, CTLs, and NK cells.
It is a potent activator of macrophages inducing an increase in metabolic, phagocytic, and killing activity.
Describe the process of Inhibition of CD8 T cell response.
Exhausted CD8 T cells show reduced production of IFN-gamma and increased expression of PD-1 inhibitory receptor. Inhibitory signals from PD-1 block the activation of CTLs.
Name and describe the two methods of killing of target cells by CTLs.
1) Complexes of perforin and granzymes are released from the CTL by granule exocytosis and enter target cells. Granzymes are delivered into the cytoplasm of the target cell by perforin- dependent mechanism and will induce apoptosis.
2) FasL is expressed on activated CTLs, engages Fas on the surface of target cells, and induces apoptosis.
What is the only cell capable of activating naive CD8 cells?
DC.
