Inflammation and Neutrophils Flashcards
What is a type of granulocyte?
Neutrophil
A neutrophil is also known as PMN. What does this stand for?
Polymorphonuclear leucocyte
Where does neutrophil come from?
Recruited from the Bone Marrow
Large amounts
The action of neutrophil
Short lived (6hrs)
First line of defense
Detect and phagocytose pathogens
Killing mechanism of neutrophils
Lysosomal Killing mechanisms
- granules
-peptides and enzyme
Which chemokine initiates the recruitment of neutrophils?
IL-8, C5a
Attracts neutrophil to site of infection
Example of enzyme/
Myeloperoxidase
Green
Formation of pus
What cell produces histamine?
Mast cell
First line of defense
Increase vessel leakiness
Mechanism
Leukocyte Extravasation
Key steps of leukocyte extravasation
- Chemoattraction
- Tethering and rolling
- Migration
What is chemoattraction?
Sensing of pathogen in the tissue
A type of Leukocyte is?
Neutrophil
Why do leukocytes carry receptors?
Recognize chemokines
What cells line the blood vessel?
Endothelial cells
What do endothelial cells carry?
Adhesion molecules
-E/P selectin
What are expressed by leukocytes?
Glycan structures
What are in between 2 endothelial cells?
Tight junctions
Where are leukocytes found?
Blood vessel lumen
What is expressed on the surface of neutrophils and what does it interact with?
Sialyl Lewis X (sugar like structure)
Interacts with P/E selectin on endothelial cell
LFA-1 inactive integrin
Binds to selectins on endothelial cell
Receptor binding on neutrophil and endothelial cells facilitates…
Transient adhesion and slowing down of neutrophil
Lymphocytes express
L-selectin
Up regulation of cytokines will increase expression of …
P/E selectin
Tighter interaction of neutrophil and endothelial cell is facilitated by
LFA-1 inactive integrin
Migration
Squeeze through tight junctions
How is LFA-1 activated?
Cross-linking
Conformation Change
What is the arrest stage?
- Chemokine - IL-8, C5a
- ICAM-1, activation of endothelial cells
-> increases expression of adhesion molecules - LFA-1 Active Integrin - conformation change
-allows tighter binding
Extravasation
Open tight
Neutrophil squeezes between endothelial cells into tissues
attracted by chemokines at the site of infection
Phagocytosis and effector mechanism directed at the pathogen
Co-receptors for HIV entry
CXCR4 (T cells)
CCR5 (monocytes)
