T Cell Effector Mechanisms Flashcards
2 primary ways effector T cells differ form naive T cells
- Do not require B7 to become activated
2. Express different surface adhesion molecules that direct them to tissues and inflammatory sites
L-selectin located on ____
naive CD4 and CD8 cells and effector CD4 cells but NOT CD8 cells
LFA-a located on _____
naive and effector T cells, higher concentration on effector
VLA-4 located on ____
effector T cells only, binds VCAM-1 to allow effector T cells to enter inflammatory tissue
CD45Ra located on ____
naive T cells only
CD45Ro located on ____
effector and memory T cells
CD8 Effector T cells (CTLs)
initiate programmed cell death
3 effector molecules of CTLs
perforin-forms pores in the cytoplasmic membrane of the host cell
granulysin-forms pores, has antimicrobial function
granzymes- initiate the apoptotic pathway in host cells via capsize cascade
All released when CTL degranulates
Fas ligand, additional effector molecule of CTLs
FAS ligand-binds 3 copies of Fas on host cell, adaptor proteins activate capsize 8 and 3, once 3 is activated it cleaves iCAD and activates the DNAse leading to cell death
Released when CTL degranulates
T/F one CTL can kill many infected host cells?
true
IFN-gamma
as an effector molecule of CTL’s it’s important function is to drive differentiation of Th0»>Th1
How do CTL’s prevent killing cells other than infected host cells when they degranulate?
Polarization
2 most important effector functions of Th1
- supply secondary activation to B cells
2. activate macrophages
macrophage activation by Th1
CD-40 ligand on the T cell binds CD-40 on the macrophage and T cell produces IFN-gamma which activates the macrophage-makes it more phagocytic, a better APC, and more bactericidal
activated macrophages produce
- NO and ROS-makes them more bactericidal
2. More MHC class I/II and B7-making it a better APC
B cell activation by Th1
promotes class switching to strongly opsonizing Igs-IGG1 and IgG3
granulomas
prevent pathogen dissemination
composed primarily of macrophages (fuse to form giant multinuclear cell) with Th1 effector cells around periphery
Patients who lack CD40 or CD40 ligand cannot produce____
granulomas, Th1 cells are required for this formation
Th17 cytokines
IL-17 (neutrophil chemotractant) IL-22 (antimicrobial function)
Tregs recquire B7 costimulation T/F
true (uses CTLA-4 and B7)
IL-2
produced by Th1, CTLs and naive T cells
induces proliferation of activated T cells
IFN-gamma
produced by Th1 and CTLs
macrophage activation
TNF-beta
produced by Th1 and CTLs
macrophage activation
IL-4
produced by Th2 promotes class switching to IgE
IL-5
produced by Th2 promotes class switching to IgA
IL-10
produced by Th2 and Tregs
anti-inflammatory effects that result in an inhibition of cytokine release by macrophages
inhibition of T cell activation
IL-3
produced by Th1/2 and CTLs
serves as a growth factor for hematopoietic progenitor cells in the bone marrow
TNF-alpha
produced by Th1/2 and CTLs
serves as an activation signal for macrophages and as a activator of vascular endothelium allowing the macrophages to get where they need to go essentially
GMCSF
produced by Th1/2 and CTLs
serves as a growth factor for hematopoietic progenitor cells in the bone marrow resulting in increased production of macrophages and granulocytes.
TGF-beta
anti-inflammatory cytokine produced by Tregs
inhibits T cell activation
IL-17
produced by Th17
signal for induction of neutrophil chemokines by endothelial cells
IL-22
produced by Th17
serves as a signal for induction of antimicrobial peptide production by endothelial cells
Fas Ligand on Th1 cells
allows them to deactivate/kill worn out macrophages
CD40 ligand
Th1 produces CD40 ligand which binds CD40 receptor on macrophages
Effector T cells also activate B cells through CD40 mechanism
T/F Patients without CD40 ligand cannot activate macrophages to form granulomas?
true
cytokine receptors are
JAK/STAT tyrosine kinases
