T-Cell Effector Mechanisms Flashcards
Processes 1. Homing to Lymph Tissue, High Endothelial Venules i. Rolling Adhesion: L-selectin ii.. Rolling Adhesion: CCR7 iii. Stationery Adhesion: general integrins (LFA-1) Diapedesis: S1P leads a cell out of lymph nodes 2. Homing to infected peripheral tissue i. Rolling Adhesion: E and P selectin ligand ii. Stationery Adhesion: LFA-1 and VLA-4 (integrins) iii. diapedesis 3. TH1 Response- classic macrophages activation a. macrophages present antigen b. CD4 cells express CD40 li
selectins
f(x): rolling adhesion
cell: expressed by endothelial cells
wh: cell adhesion molecules that bind to selectin ligands expressed on Tcells during homing
integrins
f(x): stationery adhesion during lympohcyte homing in inflammation
cells: expressed by T cells
wh: cell adhesion molecules
examples: LFA-1 (general), VLA-4 (peripheral tissue)
chemokines
small cytokines that can induce chemotaxis
L selectin
f(x): cause rolling adhesion
cells: endothelium of high lymphatic venules
wh: endothelial cells/ tissue express L-selectin and CC-L19 and CC-L21to attract naive lymphocytes.
LFA-1
F(x): an integrin that promotes stationery adhesion
cell: expressed by Tcells
wh: expressed by lymphocytes during rolling, it binds to ICAM and VCAM ligands expressed on enothelial cells/ tissues cells
CC-R7
f(x): homing to lymphatic tissue
cell: expressed by naive lympohcytes
wh: expressed by naive lymphocytes. They bind to its ligand, CC-L-19 and CC-2, during they enter rolling due L-selectin expressed on resident cells
E and P selectin ligand
F(x): rolling adhesion
cells: activated T-cells
Wh:cytokines at sites of inflammation induces expression of E/P selectin ligands. Causes rolling, the first step in adhesion
VLA-4 / LFA-1
F(x): stationery adhesion
cells: activated T-cells
Wh: cell adhesion molecules (integrins) that are expressed on rollng
CXC-R3
F(x): homing/ adhesion
cells: activated T-cells
Wh: one of many receptors that cause homing of activated T-cells to infected tissue. They bind to their respective ligand, CXC-L10
L selectin ligand
F(x): rolling adhesion
cells: high endothelial venules
Wh: expressed to cause rolling adhesion in Naive T-lymphocytes
ICAM-1 or VCAM-1
F(x): stationery adehsion
Cells: Endothelial Cells/ Resident Cells
Wh: Ligand for integrins (LFA-1/VLA-4) expressed during rolling by Tcells
CCL19 or CCL21
F(x): homing/ adehsion Cells: Endothelial Cells Wh: ligands for CC-R class receptor expressed on Tcells and other cells during homing
E or P selectin
F(x): rolling adehsion
cells: endothelial cells
Wh: bind to E and P ligands expressed on activated T lymphocytes and lead to weak binding (rolling) at sites of inflammation
CXCL10
F(x): homing/ adhesion
Whr: endothelial cells
Wh: ligand for homing chemotaxis receptors
VLA-4 and LFA-1 are also known as
Integrins
IL-12
induces differentiation of naive CD4 cells to mature T cells
produced by macrophages during bidirectional interaction with T cells
IFN gamma
Effector T1H cells secrete IFN gamma and express CD40L to promote microbicidal activities of macrophages
T1H cells: what are their primary effector mechanisms?
activation of macrophages with IFN gamma and CD40L
Effector Mechanisms of Macrophages
- killing of phagocytosed bacteria
- secretion of cytokines (TNF, IL-1, IL_12, chemokines)
- increased expression of MHC and costimulators
TH2 effector mechanisms
- helminth defense: IL-4 and IL-5 production stimulates eosinophils and mast cells
- inhibition of classic macrophages activation: IL-4, IL10
- alternative macrophage activation: IL4, IL13
Th17 cells effector mechanisms
- inflammation recruits monocytes and neutrophils
2. defensins: function like locally produced endogenous antibiotics
classically activated macrophages
stimulation with IFN-gamma, usually through a TH1 pathway
alternative activation of macrophages
TH2 mediated with IL-4, and IL-13
a. causes tissue repair and fibrosis
b. balances effects of TH1 cells
IL-4
stimulates the production of IG3 antibody which binds to Fc receptors on mast cells and eosinophils
