Studies on the improvement of leucodepletion performance of the Haemonetics MCS plus for production of leucodepleted platelet concentrate

With the implementation of universal leucodepletion, an in-line, negatively charged LRF6H leucodepleting filter became an essential part of the Haemon etics MCS+ plateletpheresis system. A larger-scale (968) study using the st andard protocol revealed a 2.79% leucodepletion failure rate (standard < 5 x 10(6) leucocytes per adult therapeutic dose). Factors influencing the eff icacy of the filter were investigated. The pH of the filtrate was 7.0, the temperature 28<degrees>C and filtration rate 80 ml/min. Reduction of the fi ltration rate to 30 ml/min (784 doses) reduced leucodepletion failure to 0. 38%. Measurement of the leucocyte count, pre- and post-filtration of the pl atelet products, revealed that donations from 1% of donors contained substa ntially larger numbers of leucocytes in pre-filter samples (300-1500/(mu)l) than in control samples (35-70/(mu)l). This number tends to increase progr essively with subsequent donations in these individuals, leading to leucode pletion failure, whilst peripheral leucocyte counts remain normal. The new continuous filtration protocol (version C) using a less impact filter LRF-X L and a lower (7 ml/min) head pressure was also effective but failure still occurred twice on one of the donors who persistently showed high pre-filte r count. We conclude that leucodepletion failures in the Haemonetics system are related to both donor leucocyte (i.e., being light and non-adherent) a nd operational/filter performance.