The treatment of selected refractory autoimmune diseases has been complemented by the use of Protein A (Prosorba column) immunoadsorption. US Food and Drug Administration-approved clinical applications include idiopathic thrombocytopenia purpura (ITP) and rheumatoid arthritis (RA). Other common off label uses include thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). Less common experimental uses in diseases in which efficacy has been reported include autoimmune CNS syndromes, peripheral neuropathies, autoimmune pancytopenia, hemolytic anemia and solid organ transplant rejection. Prosorba column treatment is generally well tolerated but a small proportion of treated patients experience chills, fever, tremor, hypotension and rash. The mechanism of action suggested for the efficacy of the column is the restoration of normal immune balance and normal tolerance. Observations in ITP has suggested that column treatment stimulates a rise in anti-idiotype antibody directed against antiplatelet antibodies, effecting a decrease in pathogenic antiplatelet antibodies and immune complexes.