Leukapheresis

Leukapheresis is a laboratory procedure in which white blood cells are separated from a sample of blood. This may be done to decrease a very high white blood cell count in individuals with cancer (leukemia) or to remove white blood cells for transfusion. In the case of cancer, usually hematological malignancies such as acute leukemias, there are white blood cell counts high enough to cause hemostasis and "sludging" in the capillaries. This can effect retinal vasculature leading to vision changes, pulmonary vasculature leading to shortness of breath from decreased efficiency in oxygen exchange, as well as other organ systems such as the brain which would become clinically apparent with neurological deterioration of a patient from cerebrovascular compromise.

Alternatively, only granulocytes, macrophages and monocytes can be removed, leaving the lymphocyte count largely unchanged. This is used as a treatment for autoimmune diseases such as ulcerative colitis and rheumatoid arthritis, where these cells play an active part in the inflammation process.