Leukapheresis
Leukapheresis () is a laboratory procedure in which white blood cells are separated from a sample of blood. It is a specific type of apheresis, the more general term for separating out one particular constituent of blood and returning the remainder to the circulation. Leukapheresis may be performed to decrease a very high white blood cell count, to obtain blood cells from a patient (autologous) or donor (allogeneic) for later transplant into the patient, or to obtain cells for research purposes. In the case of hematological malignancies such as chronic leukemias, white blood cell counts may be high enough to cause leukostasis and "sludging" in the capillaries (acute leukemias have a more variable white cell count whereas chronic cases typically have higher white cell counts). This can affect 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. Leukapheresis may be performed to obtain the patient's own blood cells for a later transplant. White blood cells may be removed to protect them from damage before high-dose chemotherapy,