The low throughput protein A adsorber: An immune modulatory device for the treatment of rheumatoid arthritis

For the purgating of pathogenic antibodies or immune complexes (IC), several adsorbers have been developed. The staphylococcal protein A-based PROSORBA® adsorber shows very limited adsorption volume of circulating autoAb and/or circulating IC. In our small pilot trial, similar changes of humoral diagnostic parameters and cellular characteristics were observed in the PROSORBA®-treated patients and in a patient successfully treated with TNF Ab for rheumatoid arthritis, suggesting a TNF antagonising effect of PROSORBA®. We propose as a hypothesis an adsorber-catalysed conversion of a small, tissue penetrating, hardly detectable, non-complement-binding, TNF-inducing dimeric IgG1-rheumatoid factor (RF) into an endogeneously clearable species of aggregated and complement-binding IC. The pathophysiological backgrounds of SPA and IgG1-RF are broadly discussed. © Georg Thieme Verlag KG Stuttgart.