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

1
Q

selectins

A

f(x): rolling adhesion

cell: expressed by endothelial cells
wh: cell adhesion molecules that bind to selectin ligands expressed on Tcells during homing

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2
Q

integrins

A

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)

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3
Q

chemokines

A

small cytokines that can induce chemotaxis

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4
Q

L selectin

A

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.

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5
Q

LFA-1

A

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

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6
Q

CC-R7

A

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

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7
Q

E and P selectin ligand

A

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

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8
Q

VLA-4 / LFA-1

A

F(x): stationery adhesion
cells: activated T-cells
Wh: cell adhesion molecules (integrins) that are expressed on rollng

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9
Q

CXC-R3

A

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

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10
Q

L selectin ligand

A

F(x): rolling adhesion
cells: high endothelial venules
Wh: expressed to cause rolling adhesion in Naive T-lymphocytes

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11
Q

ICAM-1 or VCAM-1

A

F(x): stationery adehsion
Cells: Endothelial Cells/ Resident Cells
Wh: Ligand for integrins (LFA-1/VLA-4) expressed during rolling by Tcells

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12
Q

CCL19 or CCL21

A
F(x): homing/ adehsion
Cells: Endothelial Cells
Wh: ligands for CC-R class receptor expressed on Tcells and other cells during homing
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13
Q

E or P selectin

A

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

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14
Q

CXCL10

A

F(x): homing/ adhesion
Whr: endothelial cells
Wh: ligand for homing chemotaxis receptors

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15
Q

VLA-4 and LFA-1 are also known as

A

Integrins

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16
Q

IL-12

A

induces differentiation of naive CD4 cells to mature T cells

produced by macrophages during bidirectional interaction with T cells

17
Q

IFN gamma

A

Effector T1H cells secrete IFN gamma and express CD40L to promote microbicidal activities of macrophages

18
Q

T1H cells: what are their primary effector mechanisms?

A

activation of macrophages with IFN gamma and CD40L

19
Q

Effector Mechanisms of Macrophages

A
  1. killing of phagocytosed bacteria
  2. secretion of cytokines (TNF, IL-1, IL_12, chemokines)
  3. increased expression of MHC and costimulators
20
Q

TH2 effector mechanisms

A
  1. helminth defense: IL-4 and IL-5 production stimulates eosinophils and mast cells
  2. inhibition of classic macrophages activation: IL-4, IL10
  3. alternative macrophage activation: IL4, IL13
21
Q

Th17 cells effector mechanisms

A
  1. inflammation recruits monocytes and neutrophils

2. defensins: function like locally produced endogenous antibiotics

22
Q

classically activated macrophages

A

stimulation with IFN-gamma, usually through a TH1 pathway

23
Q

alternative activation of macrophages

A

TH2 mediated with IL-4, and IL-13

a. causes tissue repair and fibrosis
b. balances effects of TH1 cells

24
Q

IL-4

A

stimulates the production of IG3 antibody which binds to Fc receptors on mast cells and eosinophils

25
Q

Il-13

A

works with IL4 to produce alternative macrophage activation

26
Q

fun fact: lepromatous leprosy

A

destructive, associated with a defective in TH1 activation

27
Q

fun fact: tuberculoid leprosy

A

less destructive, intact TH1 activation

28
Q

Fas Ligand

A

f(x): execution of infected cells

cells: expressed on cytotoxic t cells
wh: ligand for death receptor on infected cells , causes a signaling cascade that causes apoptosis without perforation. *likely plays a minor role compared to granzyme mediated death

29
Q

Fas aka

A

CD95
whr: infected cells
wh: receptor for Fas ligand on cytotoxic T cells
f(x): leads to apoptosis without granules being shed. *likely plays a minor role compared to granzyme mediated death

30
Q

Granzymes

A

cleave and activate capsases in target cells

31
Q

perforin

A

makes cell membranes less stable and allows rapid diffusion of granzymes

32
Q

NK cells

A

recognize an absence of MHC I and kill cells