Transfusion medicine
Apheresis
Leukocytapheresis

Author: Huy Phu Pham, M.D., Garrett S. Booth, M.D., M.S. (see Authors page)

Revised: 3 November 2017, last major update April 2014

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Leukocytapheresis therapeutic leukapheresis [title]

Cite this page: Pham, H.P., Booth, G. Leukocytapheresis. PathologyOutlines.com website. http://pathologyoutlines.com/topic/transfusionmedleukocytapheresis.html. Accessed November 18th, 2017.
Definition / general
  • In this topic, we only discuss therapeutic leukapheresis as a treatment for leukostasis
  • Hyperleukocytosis:
    • Generally defined as white blood cell (WBC) count or blast count > 100,000/µL
    • Usually due to acute or chronic leukemia
    • Can lead to hyperviscosity / leukostasis syndrome
  • Hyperviscosity / leukostasis symptoms:
    • Cerebrovascular insufficiency (altered mentation, TIA, stroke)
    • Pulmonary complications (dyspnea, hypoxemia)
    • Disseminated intravascular coagulopathy
  • Usually associated with:
    • AML with WBC > 100,000/µL
      • Incidence of AML with WBC > 100,000/µL is 12 - 18% in children and 5 - 18% in adults
      • Can happen in patients with blast count < 50,000/µL if they have AML M4 or M5 variant
    • ALL with WBC > 400,000/µL (< 3% of ALL patients)
Vascular access
  • Usually performed emergently using femoral apheresis or a dialysis catheter, which do not require radiographic confirmation
  • Central venous catheter, which requires radiographic confirmation, can be used in nonemergent situations
Indications
  • For therapeutic procedure, the American Society for Apheresis (ASFA) delineates leukapheresis based on the acuity of the clinical presentation
    • Symptomatic leukostasis - ASFA category I
    • Prophylaxis - ASFA category III
Volume exchanged and technical details
  • 1.5 - 2 blood volume is usually performed for therapeutic leukapheresis procedure
  • This usually reduces the WBC count by 30 - 60% although predicting the postprocedural WBC count is difficult due to mobilization of leukocytes from extramedullary sites
  • 6% hydroxyethyl starch (HES):
    • May be used to enhance separation of WBC from other blood components
    • Recommended to remove mature cells such as in CML
    • Is a volume expander excreted via urine so must evaluate patients for cardiovascular and renal status prior to use
  • For therapeutic procedures, replacement fluid is usually not indicated - usually less than 15% of the total blood volume is removed
    • Normal saline can be used to maintain blood pressure throughout the procedure
    • For pediatric patients or in patients where the volume removal is > 15% of the total blood volume, 5% albumin replacement can be used for fluid replacement
  • RBC units may be used with caution to prime the apheresis machine in in patients with severe anemia but undiluted RBCs can increase the blood viscosity
Adverse events
  • Leukapheresis is an apheresis procedure, with its typical complications
  • Also complications from the underlying leukemia, hypotension, citrate related toxicity, bleeding and infection
Treatment
  • Therapeutic leukapheresis is not curative; WBC reduction is short lived and only a bridging therapy to definitive treatments such as chemotherapy
  • Symptomatic leukostasis treatment:
    • Can be performed daily or as needed to treat leukemic patients with high WBC count with hyperviscosity syndrome
      • WBC count has a poor correlation with clinical symptoms; thus defining a WBC or blast goal is not optimal
      • Treatment should be continued until symptoms are resolved and WBC or blast count < 400,000/µL in ALL patients or < 50,000 - 100,000/µL in AML patients
    • Chemotherapy should be given concurrently with leukapheresis to prevent the rapid reaccumulation of WBC and blasts
    • Leukapheresis might decrease early death in leukemic patients with hyperviscosity but does not appear to increase overall survival
  • For prophylaxis:
    • Leukapheresis is not superior to aggressive chemotherapy and supportive care
    • Might be useful in children with ALL and WBC > 400,000/µL (50% of these patients develop pulmonary complication from leukostasis)
    • Goal:
      • ALL: WBC or blast count < 400,000/µL
      • AML: WBC or blast count < 100,000/µL