[Role of plasmapheresis and immunoadsorption in salvage therapy of rheumatological diseases].

Many rheumatological diseases are either caused by specific known proteins, such as antibodies or mediated by a plethora of cytokines. Both the unspecific immunosuppressive therapy and the specific action of biologics usually require time to be effective; therefore, extracorporeal forms of treatment are increasingly being employed in severe forms of rheumatological diseases as well as in patients who cannot tolerate pharmacological treatment or where the risk of pharmacological treatment may outweigh the potential benefits. Therapeutic plasma exchange (TPE) removes not only pathogenic substances, such as autoantibodies, lipoproteins and circulating immune complexes from the plasma but also cytokines. The removed plasma that is discarded has to be substituted by blood products, e.g. human albumin or fresh frozen plasma. Fresh frozen plasma is always used when missing plasma components must be replenished, such as ADAMTS-13 in thrombotic thrombocytopenic purpura (TTP). The separated plasma can be further processed by pumping into a hollow fiber filter (cut-off of ~700 kD) and in this way low-density lipoprotein cholesterol and IgM can be eliminated. This treatment mode, called cascade filtration is used to treat diseases, such as Waldenström's macroglobulinemia and cryoglobulinemia. A specific way to remove antibodies is by immunoadsorption in which the antibodies are specifically removed by an adsorber. For this procedure there is no need to substitute blood products. This review article describes the principles of the two different treatment methods, the advantages and disadvantages and also summarizes the current evidence for their use in rheumatological diseases.