Cellular Innate Immunity: Neutrophils Flashcards
Phagocytes
Cells that protect the body by ingesting (phagocytosing) harmful foreign particles, bacteria, and dead or dying cells.
Cells of the Immune System
Innate Immune Cells
- Neutrophils
- Macrophages
- Dendritic Cells
- NK Cells
- Eosinophils
- Basophils
Innate immune cells and their function
Neutrophils
- Phagocytosis and intracellular killing
- Inflammation and tissue damage
Innate immune cells and their function
Macrophages
- Phagocytosis and intracelullar killing.
- Extracellular killing of infected or altered self targets.
Innate immune cells and their function
Dendritic Cells
- Tissue repair
- Antigen presentation for specific immune response
Innate immune cells and their function
NK Cells
Killing of virus-infected and altered self targets
Eosinophils
Killing of certain parasites
Basophils
Modulate Immune Response to allergens
Hematopoietic orgini of neutrophils or Polymorphonuclear neutrophils (PMNs) cells
Neutrophil homeostasis and life cycle
Neutrophils/Polymorphonuclear Neutrophils (PMNs) cells
- 6x10^7/minute released into circulation
- Live max 10 hours (1/2 life = 7 hours)
- About 40-60% of white blood cells ar PMNs
- Kill microbia by Oxygen-dependent and independent mechanism
Factors that increase PMN #s
Stress
Injury
Infection
Upregulation of cytokines and inflammatory mediators
Neutrophil response to infection
Circulate for 7 hours
Respond to SOS signals:
* N-formyl methionine-containing peptides
* Clotting system peptides
* Complement products
* Cytokines released by tissues and macrophages
PMN Response:
* Vascular adherence
* Diapedesis
* Chemotaxis
* Activation
* Phagocytosis and killing**
Blood neutrophils
Neutrophil Chemotaxis
- Neutrophils are very motile
- Move by rearranging cytoplasmic microfilaments and microtubule
- Portions that face upstream (leading edge) in chemotactic gradient form structure called lamellipodium
- Cytoplasm is densely packed with microfilaments
- Portions face downstream gradient (trailing edge) form knob-like uropod.
Effectiveness of chemotaxis
Methods to study Neutrophil
Chemotaxis