Further studies to evaluate methods of leucoreduction to prevent alloimmune platelet refractoriness and induce tolerance in a dog platelet transfusion model.

OBJECTIVES: Three leucoreduction filters were evaluated - when used alone or combined with centrifuge leucoreduction (C-LR) - to prevent alloimmune platelet refractoriness in a dog platelet transfusion model. MATERIALS AND METHODS: Donor platelet-rich plasma (PRP) or buffy coat (BC) platelets were either filter leucoreduced (F-LR) or F-LR/C-LR, (51) Cr radiolabelled and transfused. Weekly transfusions were given for up to 8 weeks or until platelet refractoriness. Recipients who accepted treated transfusions were then given non-leucoreduced (non-LR) platelets to determine whether donor-specific tolerance had been induced. RESULTS: Acceptance of F-LR PRP transfusions ranged from 29% to 66%. F-LR/C-LR transfusions prepared from PRP were accepted by 92%, from BC by 63% and from pooled PRP by 75% of recipients (p=NS); overall acceptance rate of F-LR/C-LR transfusions was 83%. Tolerance to subsequent non-LR transfusions occurred in 45% of the F-LR-/C-LR-accepting recipients unrelated to DR-B compatibility between donors and recipients (P = 0·18). CONCLUSION: In a dog platelet transfusion model, acceptance of donor platelets required combining F-LR with C-LR as apparently each process removes different immunizing WBCs.

Extended storage of autologous apheresis platelets in plasma.

BACKGROUND AND OBJECTIVES: The purpose of our studies was to determine the effects of extended platelet storage on poststorage platelet viability. MATERIALS AND METHODS: Normal subjects were recruited to donate platelets using two different apheresis systems: either the COBE Spectra (n = 58) or the Haemonetics MCS+ (n = 84). Platelet recovery and survival data from the two systems were compared with each other and with in vitro measurements of the stored platelets. RESULTS: There were no significant differences in either platelet recoveries or survivals between the two machines between 1 and 8 days of storage. Combining the data from both machines, platelet recoveries decreased by 2.6% and survivals by 0.3 days/storage day. In vitro assays did not predict either platelet recoveries or survivals during storage for 5-8 days. After 9 days of storage, pHs were unacceptable (≤ 6.1), suggesting that 8 days will be the longest possible storage time. CONCLUSIONS: These data suggest that, if stored platelet bacterial contamination issues are resolved, significant extension of platelet storage times is possible.