White blood cells are the soldiers that constitute the immune system of the human body. In leukopenia there is a diminished white blood cell count. When this happens, the immunity is severely weakened and the individual is at a greater risk of infections. Leukopenia may be caused by diseases, medications, and genetic deficiencies.
White blood cells
White blood cells are also termed leukocytes. The Greek word ‘leuko’ means white and ‘cyte’ means cell. Normally there are around 7000 white blood cells per microliter of blood. This forms around 1% of the total blood volume in healthy adult individuals. A decrease below the lower limit is called leukopenia.
Leukocytes are classified according to the presence of granules within them. The ones with granules are the granulocytes while the ones without are the agranulocytes.
Granulocytes are also called polymorphonuclear leukocytes. These possess granules which are actually membrane-bound enzymes acting on the invading organisms that have been engulfed by the cell.
There are three types of granulocytes that are named according to their staining properties:
Agranulocytes are also called mononuclear leukocytes and do not have granules in their cytoplasm. These contain some azurophilic granules, which are actually lysosomes that help in killing the invading organism. The cells include lymphocytes, monocytes, and macrophages.
The most common form of leukopenia is neutropenia. Normally Neutrophils comprise about 45 to 75 percent of the total white blood cell count. These are the most important initial fighters of the immune system. They are responsible for fighting bacterial, fungal, viral, and parasitic infections.
Neutropenia raises the risk of bacterial infections. If the condition is not treated early this may lead to life threatening infections, septic shock and even death.
Diagnosis of leukopenia and neutropenia
A complete blood count helps in diagnosis of leukopenia and neutropenia. Neutropenia in adults is defined as an absolute neutrophil count of less than 500 cells per microliter (µL) of blood. Counts less than 1000 cells/µL are dangerous and may raise the risk of infections.
Management of leukopenia
Treatment of leukopenia depends on the cause of the condition. For example, if there is a bone marrow suppression due to medications like anti-cancer chemotherapy, stopping the drug may often cause recovery in the white blood cell counts.
Neutropenia is also associated with radiation treatment affecting the bone marrow. Once the therapy is stopped the counts may recover. Leukopenia caused due to bacterial or fungal infections may be treated with appropriate antibiotics and antifungals respectively.
Those with genetic conditions leading to leukopenia may need granulocyte colony-stimulating factor and other bone marrow–derived growth factors to stimulate production of the WBCs.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)