The case for a new approach for documenting platelet viability

Methods of radiolabeling platelets (PLTs) have been available since 1958 (Cr-51) and 1979 (In-111) and have been used to assess candidate PLT products for transfusion by infusion into autologous volunteers. No minimum criteria defining acceptable results for licensing have been agreed to, however. In vivo recoveries of fresh PLTs in normal volunteers vary from 40 to 80 percent, and individual volunteers tend to repeat a low or high recovery in subsequent studies, It has become standard to compare test and control products in individual donors at the same time with the two isotopes. The current procedure of use of a currently licensed product at the end of its licensed storage interval as the control has problems. It has been proposed to use fresh PLTs as the control and to express the test results relative to that control. It is also proposed to have the fresh control collected, labeled, and infused on the same day as the test product is infused. I have proposed that test PLT recovery be at least 66 percent of control and survival be at least 50 percent of control.