Repeated plasmapheresis with simple plastic equipment was performed on six normal donors for the purpose of obtaining platelet-rich-plasma. Plasmapheresis was performed at rates of up to 1000 ml. of plasma per week for periods up to three months. The six donors produced a total of 26.5 liters of platelet-rich-plasma, an amount which would have requried 106 separate blood donations had conventional means been used.
No significant changes in hemoglobin, platelets or white cells were observed in the donors and serum protein depletion was minimal. No reactions to intensive plasmapheresis were encountered even when the procedure was abruptly terminated. Repeated donor plasmapheresis is a convenient method for producing large amounts of platelet-rich-plasma and affords a practical means of controlling donor factors in platelet transfusion studies.