Current status of membrane plasma separation and plasma filtration techniques.

Blood and plasma processing by membranes was introduced into clinical medicine in 1979. In the meantime, membrane plasma separation (plasmapheresis) has become very satisfactory and is now a routine therapeutic procedure in many apheresis centers. Plasma fractionation by membranes (plasma filtration or cascade filtration) for unselective removal of high molecular weight pathogens from the separated plasma is technically possible but its routine clinical application is still limited to a few diseases with at least IgM-sized target proteins. The separation of IgG from albumin needed to treat many autoimmune diseases requires further development of both the membranes and the filtration technology.