Monocytosis

As monocytosis is called in medicine an increase in the number of monocytes, a fraction of white blood cells (leukocytes ) in the blood. It is a sub-form of leukocytosis.

Monocytes originate in the bone marrow. In contrast to granulocytes but no storage of these cells takes place in the bone marrow. They are released as immature monocytes or as their precursor cells (mono blasts, promonocytes ) in the blood in case of need and differentiate into macrophages to sites of inflammation, epithelioid cells or multinucleated giant cells. The number of circulating monocytes in the blood is usually relatively low.

A monocytosis occurs in chronic inflammation, for processes with increased phagocytosis and necrosis. A slight monocytosis may also be triggered as a nonspecific " stress response " by high levels of glucocorticoids.

In certain diseases of the blood, it can also lead to changes in cell morphology of monocytes. So vacuoles may occur with phagocytosed material. This can be for example red blood cells ( erythrocytes) during an immune -mediated hemolytic anemia, fungi, such as at a systemic histoplasmosis or protozoa such as leishmaniasis in a. Note that for such changes of fresh blood is more suitable for the investigation, as during prolonged storage in EDTA phagocytosis of other white or red blood cells also can take place after removal.