The goal of leukapheresis is to reduce the peripheral WBC count, a debulking of specific cell counts that have certain therapeutic indications as well as research initiatives. For patients with acute and chronic illnesses, therapeutic leukapheresis can be initiated on a stand alone or recurrent basis to help alleviate and decrease symptoms of conditions like hyperleukocytosis, a complication of various leukemias where the body makes too many WBCs. Specifically, hyperleukocytosis is an abnormal laboratory value with WBC counts greater than 100,000/μL (depending on the type of leukemia) caused by leukemic cell proliferation. Hyperleukocytosis can cause severe morbidities and mortality by inducing a life-threatening condition known as leukostasis, where the accumulated mass of white blood cells can cause tissue hypoxia and vascular destruction most often seen in the central nervous system and lungs.
For purposes outside of research, the main indication for therapeutic leukapheresis is leukostasis, which is most often seen in patients with acute myelogenous leukemia (AML), acute lymphocytic leukemia (ALL), chronic myelogenous leukemia (CML), and chronic lymphocytic leukemia (CLL). Although leukapheresis has not be proven to have an influence on any these disease states, it has been shown to temporarily alleviate symptoms and achieve significant goals of leukocyte (a type of WBC outlined in LEUKAPHERESIS PRODUCTS) reductions, especially in patients with AML.
Simply put, leukapheresis has a specific role: decrease peripheral WBC count. All these indicated conditions for therapeutic leukapheresis treatment have an increased morbidity rate in the leukemic system, thus spurring the need for leukocyte, or WBC, reduction to improve symptoms and stave off leukostasis. The following table outlines treatment guidelines for patients with acute and chronic stages of myelogenous and lymphocytic leukemia.
|TYPE OF LEUKEMIA||DESCRIPTION||LEUKAPHERESIS TREATMENT|
|Acute Myelogenous Leukemia(AML)|
Acute = short course, sharp
Myelogenous = resulting from the bone marrow
Leukemia = proliferation of WBC
|Patients with AML have large blast cells, or more immature WBCs, with symptoms of hyperleukocytosis such as anemia, thrombocytopenia, and disseminated intravascular coagulation. This excess of large blasts drastically increases blood viscosity and is the most frequent setting of therapeutic leukapheresis.||Leukapheresis can decrease WBC counts so patients can receive blood transfusions (RBCs and platelets) safely .|
|Chronic Myelogenous Leukemia (CML)|
Chronic = persisting for a long timeMyelogenous = resulting from the bone marrowLeukemia = proliferation of WBC
|Patients are treated similarly to AML, although the presentation of the blasts differ. Blasts are more mature and show more deformability in the chronic phase of myelogenous leukemia, which allows for a more accessible removal from the body with the leukapheresis technique. Thus leukostasis and the subsequent risk of death are less common in patients with CML than AML.||Multiple regimens of leukapheresis on a scheduled plan has been found to drastically reduce and keep down WBC count for patients with CML.|
|Acute Lymphocytic Leukemia (ALL)|
Acute = short course, sharpLymphocytic = pertaining to lymphocytes, a type of WBCLeukemia = proliferation of WBC
|Patients with ALL have immature blasts that are smaller than those present in patients with AML, which tends to present less symptoms of hyperleukocytosis.||Leukapheresis is still commonly used to help “debulk” the peripheral WBC count.|
|Chronic Lymphocytic Leukemia (CLL)|
Chronic = persisting for a long timeLymphocytic = pertaining to lymphocytes, a type of WBCLeukemia = proliferation of WBC
|Patients with CLL present the associated smaller blast in a more mature, deformed state that allows for easier removal than the acute phase.||Although chemotherapy is preferred treatment for CLL, leukapheresis can be used for those patients who cannot tolerate it.|
With small and maintained deformability, hyperleukocytosis is less common with these lymphocytes (i.e. they are easier to remove). Which is why leukapheresis with chronic leukemia is more effective than with acute leukemia. Although the problem persists with the chronic phase, the actual lymphocytes are in better position to be removed, thus regularly scheduled leukapheresis has proven efficacy.
Proper leukapheresis treatments can help reduce symptoms of diseases like CML but cannot cure nor change its course. Retrospective studies have shown that leukapheresis has a beneficial effect in early morbidity and mortality rates of patients with newly diagnosed AML but have shown no influence on long term survival. Leukapheresis should be used in conjunction with established methods of cancer treatments like chemotherapy (for eligible patients who can tolerate treatments like chemotherapy). A recently discovered use for leukapheresis is for management of newly diagnosed cases of CML during pregnancy, when induction chemotherapy cannot be tolerated (i.e. to prevent exposure of the fetus to cytotoxic drugs). In general, for those patients unable to tolerate chemotherapy, leukapheresis is a viable option. Additionally, research is being conducted to prove efficacy of leukapheresis treatments as a precursor to chemotherapy to help avoid or reduce leukemic symptoms such as tumor lysis syndrome.
Since leukapheresis is the most rapid method of acutely lowering a patient’s peripheral WBC count, the effectiveness of the procedure will depend on the patient: how efficiently the WBCs are removed and how quickly these WBCs are regenerated from the bone marrow. Thus, each patient’s results may differ. Every person and every leukocrit count is different.
The efficacy and efficiency of leukapheresis can statistically be measured by the ability to separate the cells (which is why some chronic conditions make it easier or harder to reduce WBC count). One way to determine this efficacy is to measure a patient’s leukocrit count. The leukocrit count is the measure of peripheral leukocytes, presented as a percentage of the cytocrit (hematocrit + leukocrit). If the leukocrit is elevated, the ability to remove these leukocytes dramatically increases. Leukapheresis treatments will also achieve greater efficacy with specific supplementations to increase WBC counts prior to treatment. Some donation centers will have patients take G-CSF (granulocyte-colony stimulating factor) drugs and steroidal supplements to increase the subsequent WBC yield.
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