Disorders of Leukocytes

Leukocyte disorders are characterized by either leukopenia, an abnormally low leukocyte count, or leukocytosis, a very high leukocyte number.

Bone marrow disorders and autoimmune and infectious diseases can result in leukopenia.

For example, multiple myeloma and aplastic anemia affect the bone marrow's ability to produce adequate leukocytes.

Similarly, autoimmune diseases like lupus and viral infections like HIV trigger the immune system to attack cells involved in leukocyte production.

In contrast, leukocytosis is often a natural response to infections. When the body detects an invading infectious agent, it releases more leukocytes into the bloodstream to combat the threat.

However, an extreme leukocyte count of 100,000 or more cells per microliter generally indicates some form of leukemia.

These blood cancers are categorized based on the speed of progression and the affected cell lineage.

For instance, acute myeloid leukemia is an aggressively spreading cancer of the myeloid lineage, while chronic lymphocytic leukemia has slow progression and affects the lymphoid cells.

In addition, infectious mononucleosis often caused by the Epstein-Barr virus increases atypical lymphocytes, which may be mistaken for monocytes.