The effect of immunoadsorption therapy by a protein A column on patients with thrombocytopenia.

Immunoadsorption therapy employing protein A columns (PROSORBA columns) was used for the treatment of patients with naturally occurring or transfusion-induced immune thrombocytopenia purpura (ITP). Plasma from one unit of blood was perfused through the columns and returned to each patient. This procedure was performed once or twice weekly. In two cases of acute ITP, platelets markedly increased, and platelet-associated IgG (Pa-IgG) and circulating immune complexes (CIC) were decreased following the treatments. A transient increase in platelets was achieved in one patient with chronic ITP. Some improved response to platelet transfusions was noticed in one patient with aplastic anemia and platelet alloimmunization. Two mechanisms are suggested for the effect of protein A column therapy: one is the stimulation of the production of anti-idiotype antibody that neutralizes platelet auto-antibody and the other is activation of complement that induces solubilization and removal of CIC containing platelet autoantibodies. Immunoadsorption by protein A column is a useful therapy for some ITP cases, especially those that are acute.