| Abstract: | Multiple units of platelet concentrate obtained by intensive plateletpheresis of patients with leukemia in remission were pooled and frozen using 4 to 5 per cent dimethylsulfoxide and retransfused during periods of thrombocytopenia. Plateletpheresis was well tolerated by all donors and an average platelet yield per unit of 0.99 × 10(11) (n = 155) was obtained. The results of 107 transfusions to 36 patients are presented. An average of 32.4 per cent of the platelets were lost during the freeze-thaw process. Freezing loss was lowest at a freezing rate of one degree C per minute, at a lower final concentration of platelets, and when polyolefin bags were used. The mean corrected posttransfusion count increment was 6,400/mul (range 600–19,000 xm2/10(11) platelets transfused). In vivo results did not correlate with freezing rate but were statistically significantly better at lower platelet (approximately 0.16 × 10(11) platelets/10 ml) concentrations. Eleven patients, including some who were refractory to random donor platelets were supported entirely with autologous platelets during reinduction therapy for leukemia. When administered prophylactically the autologous platelets seemed to prevent hemorrhage during periods of thromobocytopenia although in most patients bleeding times were not corrected posttransfusion. This study demonstrates that frozen autologous platelets can be used in the supportive care of thrombocytopenic patients. Further technical improvements are necessary before platelet freezing becomes practical for widespread use. |
