الحلقة الخامسة من سلسلة الفحوصات الطبية : كريات الدم البيضاء وحيدة الخلية Monocytes.

Monocytes
These agranulocytes, the largest cells of normal blood, are the body’s second line of defense against infection.    
They are not considered phagocytic cells when they are in the circulating blood. However, after they are present tissues for several hours, monocytes mature into macrophage phagocyte (Histiocytes), which are phagocytic cells.
Monocytes escaping from the upper and lower respiratory tracts and the gastrointestinal and genitourinary organs perform a scavenger function, clearing the body of debris and remove injured and dead cells, microorganisms, and insoluble particles from the circulating blood.
These phagocytic cells produce the antiviral agent called interferon.


Normal value
Count of monocyte: 100–500/mm 3.


What Does It Mean When Your Monocytes Are High?
Monocytosis or a monocyte count higher than 800/µL in adults indicates that the body is fighting an infection. Some conditions that may attribute to a high monocyte count include:
• Viral infections such as infectious mononucleosis, mumps, and measles.
• Parasitic infections such as malaria or leishmania (kala-azar).
• Brucellosis.
• Tuberculosis .
• Syphilis.
• Chronic myelomonocytic leukemia (a cancerous condition where the monocytes in the bone marrow begin to grow out of control)
• Sarcoidosis (growth of tiny collections of inflammatory cells in different parts of the body).
• Chronic inflammatory disease.
• Chronic ulcerative colitis.
• Some researchers believe that high monocyte levels are linked to cardiovascular diseases.
Monocytopenia or a monocyte count higher than 100/µL in adults
• Acute stress reaction
• Overwhelming infection
• Human immunodeficiency virus (HIV) infection.
•  Aplastic anemia (bone marrow injury)