Neutrophils Flashcards
What is the primary function of neutrophils?
phagocytosis and bactericidal action
What processes are necessarry for the phagocytotic and bactericidal functions of neutrophils?
stickiness for emigration through vessel walls; chemotaxis - motile response toward an attractant in tissue; ingestion/degranulation; bacteriocidal action
What may neutrophil function be compromised by?
deficiency of various humoral/cellular components; drug actions; toxic bacterial products
What are the secondary functions of neutrophils?
secretion of endogenous pyrogen when exposed to bacteria/bacterial products; contribute to pathology of certian conditions - ex. immune complex glomerulonephritis, rheumatoid arthritis
Define septecemia.
Bacteria in the bloodstream.
Define bacteremia.
Bacteria in the bloodstream.
Define diapedesis.
the process of a neutrophil passing through the endothelium of the blood vessels and into the tissues of the body
What is the fourth stage of neutrophil production?
myelocyte
What is the third stage of neutrophil production?
promyelocyte
What is the second stage of neutrophil production?
myeloblast
What is the progenitor cell type for neutrophil production?
stem cell
What are the three types of myelocytes?
neutrophillic, eosinophillic, basophilic
How are the three different types of myelocytes identified?
The three types of myelocytes are identified by the presence of specific granules in the cytoplasm
What is the fifth stage of neutrophil production?
metamyelocytes
What is the sixth stage of neutrophil production?
neutrophilic band
What is the seventh stage of neutrophil production?
neutrophilic segmenter
What is the first stage that a neutrophil cell line progenitor can be distinguished?
myelocyte
How many divisions occur during neutrophil production?
five points of division - myeloblast (one division), promyelocyte (one division), and myelocyte (about three divisions)
How many days supply of neutrophils does the body store?
In health there is about a five day supply of neutrophils in storage.
What is a neutrophilic left shift?
A neutrophilic left shift occurs during periods of increased need. When mature neutrophils in stroage are depleted, progressively younger cells are released into the blood.
WHat are the mechanicms for increased neutrophil production?
increased stem cell input; increased effective granulopoiesis in proliferation/maturation
When does increased stem cell input occur?
at the earliest demand for neutrophils
How many days from increased stem cell input until a difference is seen in blood neutrophil numbers?
4-5 days
What steps are taken to increase effective granulopoiesis in proliferation and maturation?
additional divisions; normal myelocyte attrition decreased
When may a sustained neutrophilia be noticed?
2-3 days after initial stimulus
What is neutrophil production regulated by?
granulopoietin
What is another term used to refer to granulopoietin?
CSF - colony stimulating factor
Where is granulopoietin produced?
granulopoietin is produced in the bone marrow by bone marrow macrophages
What is the stimulus for granulopoietin stimulus?
presence of bacterial products
What is the function of granulopoietin?
it is absolutly required to stimulate the mitosis of stem cells, and affects the number of divisions of any cell in the maturation series
What is neutrophil release from the bone marrow promoted by?
plasma factor or leukocytosis-inducing factor - LIF
What is LIF concentration increased by?
LIF is increased by bacterial products and in certian neutropenic disorders (origin unknown)
What is the reason for rapid neutrophilia (<2 days)?
increased rate of release
In health what are normal neutrophil kinetics?
neutrophils move slower than red blood cells and plasma through venules resulting in uneven distribution, and they hesitantly adhere to the endothelium of the vessels. these cells are not included in WBC count
What is the marginal neutrophil pool?
neutrophils adhered to the endothelium of the vessels and not included in the WBC count
What is the circulating neutrophil pool?
cells moving with the red blood cells and plasma - the neutrophil count in WBC count
In the dog, how much of the total neutrophil supply is in circulation?
about half - CNP = MNP
In the cat, how much of the total neutrophil supply is in circulation?
1/4 - MNP is about 3x> CNP
What is the average neutrophil transit time?
10 hours
How often is the body’s neutrophil supply replaced?
about 2.5 times a day
How are neutrophils lost in health?
through secretions, excretions and mucous membranes
What is an epinephrine induced neutrophilia caused by?
An epinephrine induced neutrophilia is caused by mobilization of the MNP cells
What is physoilogic neutrophilia caused by?
epinephrine (stress)