Basics of Therapeutic Apheresis

Apheresis is the separation and removal of components of blood. Whole blood from a patient flows into an automated instrument that separates it into various components either by centrifugation or by membrane filtration (size). For therapeutic apheresis (TA), the goal is generally to remove a specific pathologic component of blood to treat an underlying disease and return the remaining components back to the patient with or without replacement fluid. The replacement fluid is most often a crystalloid/colloid (albumin) or donor plasma. Common TA procedures include therapeutic plasma exchange (TPE), red blood cell exchange (RCE), and cellular reductions, including removal of platelets or white blood cells. Leukapheresis, the removal of white blood cells, can be for therapeutic purposes (such as leukoreduction for symptomatic hyperleukocytosis) or to obtain cells for preparation for immune effector cell therapies (such as hematopoietic progenitor cell transplantation or immune effector cell therapies). There are also special apheresis procedures for lipoprotein apheresis and for extracorporeal phototherapy (extracorporeal photopheresis). The purpose of this chapter is to discuss the basics of these apheresis procedures and the common indications for which they are performed.