Safe and effective plasma exchange to remove antibodies prior to xenogeneic heart transplantation in small primates

The ability of an on-line, rapid plasma exchange (PE) system to remove circulating antibodies in preparation for xenogeneic heart transplantation was studied. Plasma exchanges were performed 27 times on 13 rhesus monkeys weighing from 6.5 to 12.0 kg, using systemic heparinization, without untoward effects. Blood flow rates of 22-72 ml/min resulted in plasma collection rates of 7-22.5 ml/min. Serum immunoglobulin levels were decreased by more than 90%, and specific antiendothelial xenoreactive IgM was completely removed after two plasma exchanges. Transferrin levels were decreased 85-95%, and complement levels fell by greater than 80%. Platelets were partially conserved, with removal rates of 18-60%. All factors returned to normal ranges within 48 hours and no bleeding complications were encountered. When antiendothelial antibodies were removed in this manner, survival of a pig heart transplanted into a rhesus monkey was extended to 12 hours, from a baseline of 2 hours, without treatment.