Monocytes

Monocytes are cellular components of the blood. They are a subset of leukocytes (white blood cells). When they leave the circulating blood, they develop into macrophages scavenger cells).

Monocytes have a diameter of about 12-20 µm. This makes them the largest cells in the circulating blood.The life span of circulating monocytes is 1-3 days; as macrophages they have a life span of 2-3 months.

They are counted as part of both the specific and non-specific cellular immune systems.

Monocytes are determined as part of the differentiation of leukocytes (see “Differential blood count” below).

The procedure

Material needed

  • 4 ml EDTA blood (mix well!); for children, at least 0.25 ml.

Preparation of the patient

  • Not necessary

Disruptive factors

  • None known

Indications

  • Infections
  • Autoimmune diseases
  • Granulomatous diseases of the lung
  • Malignant (malignant) neoplasms

Normal values

Age Absolute values Percentage(of total leukocyte count)
Infants 630-3,000/μl 630-3,000/μl
Children 80-720/μl 1-6 %
Adults 200-800/μl 2-10 %

Interpretation

Interpretation of elevated values (monocytosis).

  • Physiologic: pregnancy, after extreme sports
  • Infections
    • Bacterial infections
      • Brucellosis (extremely rare)
      • Endocarditis lenta
      • Paratyphoid fever
      • Tuberculosis (TB)
      • Syphilis
    • Viral infections
      • Dengue fever (severe form)
      • Hantavirus infection
      • Infectious mononucleosis (EBV infection)
      • Morbilli (measles)
      • Parotitis epidemica (mumps)
      • Rocky mountain spotted fever (rocky mountain spotted fever; rare).
      • Varicella (chickenpox)
    • Parasitic infections
      • Malaria (severe form)
      • Leishmaniasis (Leishmania)
      • Trypanosomiasis (trypanosomes; sleeping sickness).
  • Convalescence / recovery phase after acute infections.
  • Autoimmune diseases
    • Polymyalgia rheumatica
    • Rheumatoid arthritis
    • Giant cell arteritis (formerly arteritis temporalis).
    • Sarcoidosis
    • Scleroderma (rare)
    • Systemic lupus erythematosus (SLE)
  • Granulomatous diseases of the lung: granuloma formations.
    • By inorganic and organic dusts, e.g., berylliosis, silicosis, exogenous allergic alveolitis.
    • By diseases such as sarcoidosis, histiocytosis X, granulomatous vasculitides.
  • Malignant neoplasms
    • Chronic myeloid leukemia (CML).
    • Malignant lymphoma
    • Myelomonocytic leukemia
    • Hodgkin’s disease
    • Metastatic tumors
  • Drugs
    • Antiepileptic drugs
    • Chronic, high-dose corticosteroid therapy.
    • Blood cell growth factors (G-CSF, GM-CSF, M-CSF).
    • Neuroleptics