Therapeutic plasmapheresis and plasma exchange.

Plasma exchange is a process in which large volumes of plasma, usually equivalent to one plasma volume, are exchanged with donor plasma or a plasma substitute. This permits the removal of antibody, immune complexes, inflammatory mediators, paraproteins, drugs, toxins, and other plasma constituents. Plasma exchange may also have an effect on the immune system by enhancing the function of the reticuloendothelial system, removing blocking antibody, increasing clearance of tumor cells, and making lymphocytes more vulnerable to immunosuppressive drugs. Over 100 diseases have been treated with plasma exchange with variable success. Results of controlled studies are less dramatic than those of earlier uncontrolled case reports. Reports of complications and even death have tempered initial enthusiasm. Now, over a decade since the initial promising reports began to appear in the literature, the role of plasma exchange remains undefined.