What is Margination in leukocytes?
Leukocytes, in contrast to RBCs, appear to flow primarily in the peripheral layer. This is termed margination, which is the first step in the firm adhesion of leukocytes to the endothelium. Although the deformability of leukocytes is much smaller than RBCs, lift forces are still present even for leukocytes.
What causes Margination of leukocytes?
This margination process is generally attributed to red blood cells (which normally pile up behind the larger leukocytes in capillaries) that overtake the leukocytes and tend to push them toward the venular wall.
What is the leukocyte emigration?
Leukocyte extravasation (also commonly known as leukocyte adhesion cascade or diapedesis – the passage of cells through the intact vessel wall) is the movement of leukocytes out of the circulatory system and towards the site of tissue damage or infection.
What causes leukocyte migration?
The primary step in leukocyte migration is the establishment of weak and transient adhesive interactions between leukocytes and endothelial cells of postcapillary venular walls in close vicinity to inflamed tissues (Figure 1).
What is Margination during Margination?
To facilitate the adhesion, white blood cells migrate toward the vessel walls in blood flow through a process called margination. In addition, aggregation interactions between red blood cells lead to enhanced white-blood-cell margination.
What causes Margination?
When the gap size between the cell surface and the wall becomes larger than the thickness of RBCs, margination is caused by overtaken or overtaking events.
What happens to leukocytes during Margination?
What is diapedesis and why is it important?
diapedesis (dy-ă-pĕ-dee-sis) n. migration of cells through the walls of blood capillaries into the tissue spaces. Diapedesis is an important part of the reaction of tissues to injury (see inflammation).
Which are characteristic of leukocytes?
A white blood cell, also known as a leukocyte or white corpuscle, is a cellular component of the blood that lacks hemoglobin, has a nucleus, is capable of motility, and defends the body against infection and disease.
What is emigration in inflammation?
The main characteristics of acute inflammation are the exudation of fluid and plasma proteins (edema) and the emigration of leukocytes (predominantly neutrophils). Neutrophils and other motile white cells emigrate or move from the blood vessels to the perivascular tissues and the injury (implant) site [42–44].
Where does leukocyte Diapedesis occur?
Most leukocyte diapedesis (extravasation) occurs in post-capillary venules because hemodynamic shear forces are lower in these venules. This makes it easier for leukocytes to attach to the inner wall of the vessel and squeeze out between the endothelial cells.
What do you mean by Margination?
[ mär′jə-nā′shən ] n. The adhesion of white blood cells to the endothelial cells of blood vessels that occurs at the site of an injury during the early phases of inflammation.
What is the role of lymphocyte chemotaxin in leucocyte margination and emigration?
The role of a lymphocyte chemotaxin as the stimulus for emigration in this location is unknown. To encompass the known phenomena, a general theory of leucocyte margination and emigration would predict that leucocytes selectively marginate onto acceptor molecules expressed by endothelium and extravasate in response to a chemotactic stimulus.
What is the general theory of leucocyte margination?
To encompass the known phenomena, a general theory of leucocyte margination and emigration would predict that leucocytes selectively marginate onto acceptor molecules expressed by endothelium and extravasate in response to a chemotactic stimulus. Endothelium-bound chemotaxins may function as acceptor molecules.
What does the presence of leukocyte esterase indicate?
It is a commonly used test. Leukocyte esterase is an enzyme produced by the leukocytes. This test detects the presence of leukocytes and other abnormalities associated with infection. The presence of leukocyte esterase indicates pyuria while nitrite indicates bacteriuria.
What is the primary step in leukocyte migration?
The primary step in leukocyte migration is the establishment of weak and transient adhesive interactions between leukocytes and endothelial cells of postcapillary venular walls in close vicinity to inflamed tissues ( Figure 1 ).