Monocyte

Monocyte is a type of leukocyte, part of the human body's immune system. The human body is the entire physical and mental structure of a Human Organism. An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor Monocytes have two main functions in the immune system: (1) replenish resident macrophages and dendritic cells under normal states, and (2) in response to inflammation signals, monocytes can move quickly (aprox. Macrophages ( Greek: "big eaters" from makros "large" + phagein "eat" ( Mø) are cells within the tissues that Dendritic cells (DCs are Immune cells and form part of the Mammalian Immune system. 8-12 hours) to sites of infection in the tissues and derive into macrophages and dendritic cells to elicit an immune response. Monocytes are usually identified in stained smears by their large bilobate nucleus.

Physiology

Monocyte

Monocytes are produced by the bone marrow from haematopoietic stem cell precursors called monoblasts. Bone marrow is the flexible tissue found in the hollow interior of Bones In adults marrow in large bones produces new Blood cells It constitutes 4% of Hematopoietic stem cells (HSCs are Stem cells that give rise to all the blood cell types including Myeloid ( Monocytes and Macrophages, Neutrophils Monoblasts are normally found in bone marrow and do not appear in the normal peripheral blood Monocytes circulate in the bloodstream for about one to three days and then typically move into tissues throughout the body. They constitute between three to eight percent of the leukocytes in the blood. In the tissues monocytes mature into different types of macrophages at different anatomical locations. Macrophages ( Greek: "big eaters" from makros "large" + phagein "eat" ( Mø) are cells within the tissues that

Monocytes are responsible for phagocytosis (ingestion) of foreign substances in the body. Phagocytosis is the cellular process of engulfing solid particles by the Cell membrane to form an internal Phagosome, or "food vacuole Monocytes can perform phagocytosis using intermediary (opsonising) proteins such as antibodies or complement that coat the pathogen, as well as by binding to the microbe directly via pattern-recognition receptors that recognize pathogens. An opsonin is any molecule that acts as a binding Enhancer for the process of Phagocytosis, for example by coating the negatively-charged molecules on the membrane Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily The complement system is a Biochemical cascade that helps clear Pathogens from an organism Monocytes are also capable of killing infected host cells via antibody, termed antibody-mediated cellular cytotoxicity. Vacuolization may be present in a cell that has recently phagocytized foreign matter. In general vacuole functions include Removing unwanted structural debris Isolating materials that might be harmful or a threat to the cell Containing

Monocytes which migrate from the bloodstream to other tissues will then differentiate into tissue resident macrophages or dendritic cells. Macrophages ( Greek: "big eaters" from makros "large" + phagein "eat" ( Mø) are cells within the tissues that Dendritic cells (DCs are Immune cells and form part of the Mammalian Immune system. Macrophages are responsible for protecting tissues from foreign substances but are also suspected to be the predominant cells involved in triggering atherosclerosis. Atherosclerosis is a Disease affecting arterial Blood vessels It is a chronic inflammatory response in the walls of arteries in large part due to the accumulation They are cells that possess a large smooth nucleus, a large area of cytoplasm and many internal vesicles for processing foreign material.

Diagnostic use

A scanning electron microscope (SEM) image of normal circulating human blood. One can see red blood cells, several knobby white blood cells including lymphocytes, a monocyte, a neutrophil, and many small disc-shaped platelets.

A monocyte count is part of a complete blood count and is expressed either as a ratio of monocytes to the total number of white blood cells counted, or by absolute numbers. A complete blood count ( CBC) also known as full blood count ( FBC) or full blood exam ( FBE) or blood panel, is Both may be useful in determining or refuting a possible diagnosis. Monocytosis is the state of excess monocytes in the peripheral blood. Monocytosis is an increase in the number of circulating Monocytes In humans 950/μL is regarded as at the upper limit of normal monocyte counts above this level are regarded It may be indicative of various disease states. Examples of processes that can increase a monocyte count include:

• chronic inflammation
  
• stress response
  
• hyperadrenocorticism
  
• immune-mediated disease
  
• pyogranulomatous disease
  
• necrosis
  
• red cell regeneration
  

Dendritic cells

Monocytes can be used to generate dendritic cells in vitro. Inflammation ( Latin, inflamatio, to set on fire is the complex biological response of vascular tissues to harmful stimuli such as Pathogens Immune-mediated diseases are conditions which result from abnormal activity of the body's immune system Necrosis (in Greek Νεκρός = "dead" is the name given to unnatural Death of cells and living tissue. Red blood cells are the most common type of Blood cell and the Vertebrate body's principal means of delivering Oxygen to the body tissues via the Blood Dendritic cells (DCs are Immune cells and form part of the Mammalian Immune system. ^[1]

See also

• Agranulocyte
• Complete blood count
• Hematopoiesis
• Neutrophil granulocyte
• Phagocyte
• White blood cell

References

External links

• Histology at BU 01702ooa
• Human Monocytes - Prof. Dr. Ziegler-Heitbrock