Current topics in therapeutic plasmapheresis.

Therapeutic plasmapheresis has been used for intractable diseases that cannot be cured by conventional drug therapy. Currently, the use of therapeutic plasmapheresis has been approved for 27 diseases by Japan's National Health Insurance system and is mainly categorized into three modalities: plasma exchange (PE), double-filtration plasmapheresis (DFPP), and plasma adsorption (PA). Plasma separators and/or fractionators are essential for the therapy. PE is performed for two purposes: removal of pathogenic antigens or substances in the plasma fraction and supplementation of essential factors, such as albumin and coagulation factors. PE can be used for thrombotic microangiopathy and acute hepatic failure. DFPP can be performed for selective removal of macromolecules while avoiding the use of substitution fluid (i.e., albumin or fresh frozen plasma). DFPP has now been used for conditions involving relatively larger plasma molecules, including hyperviscosity syndrome and ABO-incompatible kidney transplantation. PA can specifically remove pathogenic agents, such as low-density lipoprotein or autoantibodies, in the IgG fractions by the adsorption column and does not require substitution fluids. PA has now been used for a wide variety of neurological diseases, including chronic inflammatory demyelinating polyneuropathy. This review describes the characteristics of each modality, seeking to improve the efficacy and specificity of removal of the target substance.