Protein A-immunoadsorption (Prosorba~R column) in the treatment of rheumatoid arthritis

摘要

New pathophysiological concepts are beginning to emerge for rheumatoid arthritis (RA). Studies establishing a key role for tumor necrosis factor alpha (TNFalpha) in rheumatoid synovialinflammation led to the development of anti-TNFalpha agents, which were then proved effective. However, TNFa inactivation depresses the immune system, increasing the risk of infection. This drawback, together with the recent emphasis on anti-filaggrin autoantibody production, may rekindle interest in plasma exchange as a treatment alternative in patients with RA.For many years, plasma exchange was the only technique capable of clearing the plasma of substances with possible pathogenic effects. However, plasma exchange produced partial or disappointing results in patients with RA. Plasma exchange is a nonselective method and requires the removal of several liters of plasma (60 ml/kg on average) and its replacement by an equivalent volume of plasma substitutes such as albumin. In the 1980s, immunoadsorption was suggested asan alternative to plasma exchange for removing noxious substances from the plasma of patients with autoimmune diseases refractory to conventional treatments. Candidate diseases for immunoadsorption were autoimmune conditions due to known factors that were removable by physical, chemical or immunological techniques, such as myasthe-nia, autoimmune thrombocytopenic purpura, coagulation factor inhibitor production systemic lupus erythematosus, and idiopathic dilated cardiomyopathy .Immunoadsorption is more selective than plasma exchange, as it does not remove plasma proteins such as albumin and clotting factors. In addition, immunoadsorption does not require administration of plasma substitutes and therefore does not expose patients to the potential side effects of these compounds. Albumin preparations, for instance, are obtained from human sources and may be capable of transmitting infectious agents. In 1999, the Food and Drug Administration licensed protein A-immunoadsorption on the Prosorba~R column for patients with refractory RA.