Marginal zone
Encyclopedia
The marginal zone is the region at the interface between the non-lymphoid red pulp and the lymphoid
white-pulp of the spleen
. (Some sources consider it to be the part of red pulp which borders on the white pulp, while other sources consider it to be neither red pulp nor white pulp.)
A marginal zone also exists in lymph node
s.
compartment of bone marrow
differentiation. At least three distinct cellular markers can be used to identify cells of the marginal zone, MOMA-1, ERTR-9 and MARCO
.
from the circulation
and present the antigen to the lymphocytes of the spleen.
Experiments have shown that inert latex
beads as well as live bacteria such as Escherichia coli
and Listeria monocytogenes are trapped by the marginal zone. However, only immunogenic substances, i.e. bacteria
, are trafficked to the T and B cell zones of the white-pulp and are efficiently presented to elicit an immune response.
(Marginal-zone B cell
, abbreviated "MZ B cell") created there, capable of binding IgM
-antigen complexes. They are notable for their ability to serve several different roles in the immune system
.
Lymphoid
Lymphoid is a term used to describe lymph or the lymphatic system.In the context of lymphoid leukemia, it refers specifically to lymphocytes Lymphoid leukemias and lymphomas are now considered to be tumors of the same type of cell lineage. They are called "leukemia" when in the blood or marrow and...
white-pulp of the spleen
Spleen
The spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock...
. (Some sources consider it to be the part of red pulp which borders on the white pulp, while other sources consider it to be neither red pulp nor white pulp.)
A marginal zone also exists in lymph node
Lymph node
A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...
s.
Composition and markers
It is composed of cells derived primarily from the myeloidMyeloid
The term myeloid suggests an origin in the bone marrow or spinal cord, or a resemblance to the marrow or spinal cord.In hematopoiesis, the term "myeloid cell" is used to describe any leukocyte that is not a lymphocyte...
compartment of bone marrow
Bone marrow
Bone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...
differentiation. At least three distinct cellular markers can be used to identify cells of the marginal zone, MOMA-1, ERTR-9 and MARCO
MARCO
Macrophage receptor MARCO is a protein that in humans is encoded by the MARCO gene.-Further reading:...
.
Function
The major role of marginal zone is to trap particulate antigenAntigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
from the circulation
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
and present the antigen to the lymphocytes of the spleen.
Experiments have shown that inert latex
Latex
Latex is the stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic.Latex as found in nature is a milky fluid found in 10% of all flowering plants . It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins,...
beads as well as live bacteria such as Escherichia coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
and Listeria monocytogenes are trapped by the marginal zone. However, only immunogenic substances, i.e. bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, are trafficked to the T and B cell zones of the white-pulp and are efficiently presented to elicit an immune response.
Lymphocytes
Marginal zone lymphocytes are a type of B cellB cell
B cells are lymphocytes that play a large role in the humoral immune response . The principal functions of B cells are to make antibodies against antigens, perform the role of antigen-presenting cells and eventually develop into memory B cells after activation by antigen interaction...
(Marginal-zone B cell
Marginal-zone B cell
Marginal zone B cells are noncirculating mature B cells that segregate anatomically into the marginal zone of the spleen. This region contains multiple subtypes of macrophages, dendritic cells, and the MZ B cells; it is not fully formed until 2 to 3 weeks after birth in rodents and 1 to 2 years in...
, abbreviated "MZ B cell") created there, capable of binding IgM
IGM
IGM as an acronym or abbreviation can refer to:* Immunoglobulin M , the primary antibody against A and B antigens on red blood cells* International Grandmaster, a chess ranking* intergalactic medium* Intragroup medium - see: Intracluster medium...
-antigen complexes. They are notable for their ability to serve several different roles in the immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
.