Leukocyte Structure and Function Flashcards
What does leukocyte activation require?
A change in morphology and behavior from extracellular signal
cell surface markers expressed on surface of all blood cells (leukocytes)
<p>CD antigens (cluster of differentiation)</p>
Primary cells of innate immunity
Myeloid cells
There are about 5,000-10,000 total leukocytes (cells/ul) circulating. Which type make up the most? Which make up the least?
Neutrophils- 55-70%
Basophiles-0.5-1%
This type of leukocyte has a really round nucleus, almost same size as cytoplasm
Lymphocyte
This cell has a segmented nucleus, but it stains dark in H/S stain you probably can’t see it
basophil
What is the activated function of neutrophil?
Phagocytosis and activation of bactericidal mechanisms
Are neutrophils short lived or long lived?
Short lived; circulate for a few hours, undergo apoptosis/necrosis
How many rounds of phagocytosis do neutrophils undergo before cell death?
ONE. A single one.
What clears out dead neutrophils?
Tissue macrophages
What is the chief cell of acute inflammation?
Neutrophils
These molecules are associated with groups of pathogens, recognized by cells of innate immune system
PAMPs “pathogen associated molecular patterns”
DAMPs “danger associated”
All neutrophils express this integral membrane protein on their surface to recognize pathogens
Mannose receptor
This term describes the rapid release of reactive oxygen species and NADPH-oxidase subunites to destroy internalized bacteria
Respiratory or oxidative burst
This is a small vesicle that contains the bacterium inside
phagosome
What is a lysosome fuzed with phagosome called?
Phagolysosome
What do tertiary neutrophil granules contain?
Gelitinase (MMP-9)
What are the characteristics and role of primary / azurophilic neutrophil granules?
Dark staining, antimicrobial proteins, fuse with endosomes and empty contents. Kill ingested bacteria
What are the characteristics and role of secondary/specific/definitive neutrophil granules?
Pale, fuse with endosome, trigger respiratory burst. Release contents extracellulary
What are 3 important consequences of the Respiratory Burst?
- Increase oxygen consumption
- production of superoxide O2-
- Production of hydrogen peroxide (H2O2) and other bactericidal reactive oxygen species (ROS)
What is the primary azurophilic neutrophil granule?
What is another important one?
Myeloperoxide (MO) Sulfated Proteoglycan (Sulfated PG)
NADPH oxidase, sometimes called “phagocytic oxidase,” is in the walls of which neutrophil granule?
Secondary granules
How many subunits does NADPH oxidase have? How amny are in cytoplasm? Which ones?
5 subunits, 3 in cytoplasm: p40phox, p45, p67
What is the membrane bound component of the NADPH oxidase?
flavocytochrome b (consists of 2 subunits: gp22phox, gp91 phox)
Once activated, NADPH oxidase converts oxygen molecules to what?
Superoxide, O2-
What enzyme converts superoxide to hydrogen peroxide?
Superoxide dismutase
What enzyme breaks down hydrogen peroxide to hypochloric acid? (HOCL-)
Myeloperoxidase (MPO)-
This enzyme breaks down hydrogen peroxide to benign components such as water and oxygen
Catalase
Mutations in NADPH oxidase underlie what disease?
Chronic Granulomatous Disease (can be autosomal recessive or X-linked if mutation of gp91)
How do neutrophils aid in infection control and wound healing?
Release mediators to destroy damaged tissue; disassemble matrix proteins to allow neutrophil-microbe interaction; prevent microbe escape
How do matrix metalloproteinases (MMPs) contribute to tissue destruction from chronic inflammation?
Inflammation causes cytokines to attract more leukocytes, MMPS digest ECM»_space; tissue destruction
Both of these cells release histamine and have surface receptors for antibody
Mast cells and basophils
Basophil or Mast cell? Recruited to tissue
Basophils
Basophil or Mast cell? Source of tissue histamine
Mast cell
Basophil or Mast cell? Complete maturation in tissues
Mast cell