PROTEIN-A IMMUNOADSORPTION TREATMENT IN HEMATOLOGY - AN OVERVIEW

Staphylococcal protein A efficiently binds immunoglobulins and circula ting immune complexes (CIC) and provides an effective medium to remove immunoglobulins and CICs from plasma while sparing albumin and most c oagulation proteins. Although it activates the complement system its c linical use abrogates the need for plasma expanders necessitated by pl asma exchange. Despite anecdotal reports of utility in several hematol ogic syndromes, publications of clinical trials are available only for autoimmune thrombocytopenic purpura (AITP) and refractoriness to plat elet transfusions (RFT) associated with alloimmunization. In the forme r situation Snyder et al. (Blood 79:2237-2245, 1992) reported on 72 pa tients with AITP all of whom had failed at least two previous therapie s including splenectomy in 68%. Forty-six percent achieved improved pl atelet counts following treatment. The response was durable (8-26 mo) in all but 10%. Spleen-intact patients could not be differentiated fro m those who had been splenectomized. Both responders and nonresponders showed significant decreases in CIC and platelet-directed immunoglobu lin (PDIG), but responders achieved near-normal levels. The beneficial response of these factors, particularly in spleen-intact patients, wa rrants a prospective study. In our studies at the University of Minnes ota twelve patients with thrombocytopenia secondary to bone marrow fai lure who were refractory to platelet transfusion were treated with pro tein A immunoadsorption. Ten had demonstrable antiplatelet Abs (Anti-H LA, HPA, ABO). Seven of 12 demonstrated improved platelet counts and p ost-transfusion corrected count increments after treatment. This was a ssociated with decreased platelet utilization and clinical bleeding. A prospective controlled clinical trial is justified. (C) 1994 Wiley-Li ss, Inc.