Page 1432 - Clinical Small Animal Internal Medicine

1370 Section 11 Oncologic Disease

Therapeutic plasma exchange (TPE), a form of plasma- to collect CD34+ progenitor cells for their use in both
VetBooks.ir pheresis, is a procedure where the cell separator machine autologous and allogeneic bone marrow transplants
when treating patients with lymphoma, leukemia, and
separates and removes the patient’s plasma which is then
replaced with either donated plasma or a protein solu-
other conditions including myelodysplastic syndromes
tion such as 5% human albumin. TPE is typically used to multiple myeloma. The cells can also be used to treat
remove disease‐causing antibodies that cause a variety of and childhood neuroblastoma.
immune‐mediated diseases, including Guillain–Barré
syndrome, chronic inflammatory demyelinating poly-
neuropathy (CIDP), and myasthenia gravis. It can also be Companion Animal Apheresis
used to treat thrombotic thrombocytopenia purpura
(TTP) patients in an effort to reduce the thickness of the Plasmapheresis (the separation of plasma from blood to
blood. TPE can also be used to remove large amounts of be used in primary and supportive disease management)
medication if the need arises. is the most commonly reported apheresis procedure in
Low‐density lipoprotein (LDL) apheresis removes the veterinary literature. In horses, plasmapheresis has
LDL cholesterol from the blood of patients with hyper- been explored using continuous‐flow cell separator
cholesterolemia using two specific types of aphere- machines based on data showing that plasma harvested
sis machines approved by the US Food and Drug from equine blood using fast erythrocyte sedimentation
Administration (FDA). The Liposorber uses a filter cov- contains a high number of erythrocytes that could cause
ered with dextran that binds LDL cholesterol and recipient sensitization and evidence that bacterial con-
removes it from the circulation. Another machine, called tamination can occur using an open collection system.
HELP, uses heparin to bind and remove LDL cholesterol. In two studies, Feige et al. found that automated
Since hypercholesterolemia is usually caused by the plasmapheresis using a Blutz separator AS 104 (Fresenius,
combination of mutations in a variety of genes (espe- Stans, Switzerland) was the method of choice when
cially LDLRAP1) and lifestyle choices, treatment using compared to whole‐blood collection followed by either
LDL apheresis is usually life‐long. centrifugation or gravity sedimentation and that the
Photopheresis is a very specialized type of apheresis plasmapheresis procedure itself was very well tolerated
where the harvested white blood cells are exposed to a by the donor horses. To this author’s knowledge, the use
photoactive drug called methoxsalen which renders of TPE to treat equine patients with immune‐mediated
them sensitive to ultraviolet (UV) light. The cells are diseases has not been reported.
then exposed to UV light inside the machine and Canine plasmapheresis has also been reported
returned to the patient. This procedure can improve the using both membrane filtration and continuous‐flow
symptoms of certain conditions such as graft versus host centrifugation. Bartges et al. used discontinuous mem-
disease (GVHD), cutaneous T cell lymphoma, or organ brane filtration plasmapheresis (Therapore, Therapeutic
transplant rejection, although it is currently not known Apheresis Systems, Sarns/3M, Ann Arbor, MI) twice, in
exactly how photophoresis works. The length and num- conjunction with corticosteroids, to treat a dog with
ber of procedures needed to provide benefit are highly acquired myasthenia gravis, which dropped the AchR
variable. antibody titer by ~70%. Crump and Seshadri used
Leukapheresis is used to remove extra white blood continuous membrane filtration (Prisma CRRT and
cells from the blood in patients with diseases that can TPE Control Unit, Gambro Inc., Lakewood, CO) to
cause very high white blood cell counts, including treat a dog with immune‐mediated hemolytic anemia.
acute lymphoblastic and acute myeloblastic leukemias. In both reports, plasmapheresis was performed safely
Leukapheresis in these patients can significantly with minimal side‐effects and the dogs responded
decrease blood viscosity and also decrease the chance clinically.
of acute tumor lysis syndrome in patients starting Canine TPE has also been reported, although the
induction chemotherapy. majority of studies were performed in the 1980s. Matus
Peripheral blood stem cell collections are used to et al. used a cell separator (IBM 2997 cell separator, IBM
harvest monocytes from patients after some type of Corp., Princetown, NJ) to treat three dogs with an IgA
blood cell mobilization, such as G‐CSF (Neupogen) monoclonal gammopathy and secondary hyperviscos-
administration. A small percentage of the harvested ity. In all three dogs, one total plasma volume was
monocytes (~1–4%) are CD34+ progenitor cells that can removed and replaced with lactated Ringer’s solution
lead to complete hematologic reconstitution after some (LRS) and all three dogs responded clinically within
type of myeloablative therapy (such as total body irradia- 24 hourrs of treatment. This same group also treated
tion or high‐dose chemotherapy). This procedure is used one dog with systemic lupus erythematosus using a