Chemotaxis and Phagocyte Infiltration into tissue Flashcards
(45 cards)
define Chemotaxis
The movement of cells in response to a chemical stimulus
why is chemotaxis required?
Enables cells to accumulate where most needed
how does chemotaxis work?
Cell motility achieved by temporary attachment of
“front” of cell to a surface, and by the formation of
actin filaments which pull the back of the cell towards the front
in nature where does chemotaxis and killing occur?
in tissues
How do the leukocytes “know where to go”?
Signals release by damaged or infected tissues change the local blood vessels
what is a localized acute inflammatory response?
vasodilation, vascular permeability, leukocyte migration
what is the role of neutrophils
central role (get there 1st) attracted by IL-8 (CXCL8), C3a, C5a, Prostaglandins
whats the role of macrophages?
arrive 5-6 hr later,
attracted by CC chemokines, C3a, C5a
secrete IL-1, IL-6, IL-8 (CXCL8),TNF localized and systemic effects
name the 5 Groups of Chemical Mediators of Inflammation and Chemotaxis
A) Cytokines B) Plasma enzyme systems C ) Vasoactive amines D) Arachidonic acid metabolites E ) Chemokines
which cells secrete cytokines?
activated macrophages
name 5 cytokines
CXL8 IL-12 IL-6 IL-1b TNF-a
describe the action of IL-1b
Activates vascular endothelium and lymphocytes
local tissue destruction
increases access of effector cells
describe the action of TNF-a
- Activates vascular endothelium
- increases vascular permeability increasing entry of IgG, cells to tissues and fluid drainage to lymph nodes.
what are the systemic affects of IL-6, IL-1b and TNF-a?
IL-1b- fever and IL-6 production
TNF-a- Fever, mobilisation of metabolites and shock
IL-6- Fever and induces acute phase protein production.
what is the action of IL-6?
- Lymphocyte activation
- increased Ab production
describe the action of CXCL8?
recruits neutrophils, basophils and T cells
describe the action of IL-12
- activates NK cells,
- differentiate CD4 T cells into T helper cells.
what do Plasma Enzyme Systems do?
activates innate immune system even before microbes have entered or been detected
give an example of a Vasoactive amine
Histamine
what does Histamine do?
- In granules of mast cells, basophils, platelets
- Released by degranulation (triggered by C3a, C5a, etc.)
- Promotes arteriolar dilation, smooth muscle contraction, and venular endothelial contraction,
- Results in widening of interendothelial cell junctions with increased vascular permeability
- Vascular actions similar to Bradykinin
describe the action of Arachidonic Acid Metabolites
- AA released from cell membrane by Phospholipases which have been activated by various stimuli and/or inflammatory mediators
- AA metabolism occurs via two major enzyme pathways:
lipoxygenase and cyclooxygenase
name 3 Arachidonic Acid Metabolites in chemotaxis
prostaglandins, platelet activating factor and leukotriene b4
whats the effect of prostaglandins?
increase vascular permeability
vascular dilation
neutrophil chemotaxis
whats the effect of leukotriene B4?
neutrophil chemotaxis
