An Overview of Therapeutic Apheresis

Abstract

Haemapheresis, or more generally, apheresis is concerned with the separation and differential separation of blood. It differs from dialysis, in that the process of separation concentrates mainly on cells and high molecular weight proteins. Correspondingly different separation techniques are used. Though apheresis can be performed applying conventional off‐line centrifugal techniques, it is generally associated with the use of on‐line centrifugation in blood cell separators (nowadays prefered to be called blood separators), plasmapheresis systems or devices for the preparation of blood components serving autologous blood transfusion. Filtration through flat sheet membranes or hollow fiber membranes is also applied. The differential separation of cells or plasma is off‐line and on‐line, correlating with the different degrees of technical maturation of the secondary separation systems. These secondary techniques aim at a concentration of certain cell types (for instance of stem cells) or at the elimination of undesired cells such as T cells or erythrocytes from stem cell or bone marrow concentrates. In secondary plasma treatement, filtration or adsorption procedures compete with immunological techniques and magnetic binding or density centrifugation or combinations of several techniques.