++
SUMMARY
Therapeutic apheresis refers to several blood processing methods that are used in the treatment of diverse clinical conditions. In most cases, the disorders so treated are characterized by a specific qualitative or quantitative abnormality of the blood. In hematologic practice, apheresis procedures are used to mitigate hyperviscosity in monoclonal protein disorders or remove pathologic autoantibodies and replete important plasma proteins. Red cell apheresis is used to improve the ratio of normal to abnormal red cells in hemoglobinopathies and protozoan disease, and to remove excess red cells, red cell-associated toxins, or excess iron from the body. Leukocyte apheresis is used to reduce the circulating blast count in acute leukemias with hyperleukocytosis and platelet apheresis is used to lower a very elevated platelet count in patients with myeloproliferative neoplasms. Photopheresis is used in the treatment of cutaneous T-cell lymphoma and chronic graft-versus-host disease. Adverse effects of apheresis with current technologies are typically mild and, usually, do not prevent completion of therapy.
++
Abbreviations and Acronyms:
ADAMTS-13, von Willebrand factor cleaving metalloprotease; ARDS, acute respiratory distress syndrome; ASFA, American Society for Apheresis; CDC, United States Centers for Disease Control and Prevention; ECP, extracorporeal photochemotherapy; FCR, fraction of cells remaining; GRADE, Grading of Recommendations Assessment, Development and Evaluation; HUS, hemolytic uremic syndrome; MHC, major histocompatibility complex; 8-MOP, 8-methoxypsoralen; PUVA, psoralen plus ultraviolet A; TPE, therapeutic plasma exchange; TTP, thrombotic thrombocytopenic purpura; UVA, ultraviolet A light; VR, volume of red blood cells to be removed.
++
DEFINITION AND HISTORY
++
The term apheresis emerged in 1914 when John J. Abel, of the Johns Hopkins University Pharmacological Laboratory, demonstrated how large quantities of plasma could be removed from dogs by a process he called “plasmapheresis” (from the Greek apairesos or Roman aphaeresis, meaning take away by force).1 The treatment, by manual plasmapheresis, of hyperviscosity syndrome in patients with Waldenström macroglobulinemia during the 1950s supported the concept that a disease state causally related to a substance in the plasma can be effectively treated by removal of plasma.2,3 Today, a number of automated apheresis, or blood processing, techniques are used in the treatment of a growing list of clinical disorders. The American Society for Apheresis (ASFA) categorizes the indications for apheresis (Table 28–1) according to where apheresis fits into the management strategy for the condition under consideration.4 In addition, ASFA evaluates the individual indications (clinical entities) and issues recommendations regarding the use of apheresis in their treatment according to the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system.4,5 Table 28–2 lists the covered indications most relevant to the practice of hematology. This chapter considers the various apheresis approaches to hematologic disorders.
++