White cell-reduced platelet concentrates prepared by in-line filtration of platelet-rich plasma

The importance of white cell (WBC) reduction in platelet concentrates (PCs) for component quality is undetermined.

Eleven paired components, each derived from one of two whole-blood units given by a single donor on the same day, were studied. One PC was WBC reduced by filtration with an in-line, integral, prototype filter, and the other was produced from unfiltered platelet-rich plasma (PRP) by a standard method. In vitro tests performed on Day 1 and Day 5 were blood gases, plasma lactate, glucose, platelet ATP, mean platelet volume, morphology score, hypotonic stress ratio, extent of shape change in response to ADP, and beta-thromboglobulin. After 5 days of storage, each component pair was labeled with 51Cr or 111In and transfused for the estimation of percent recovery and survival.

PCs using the in-line, prototypic filter had a platelet loss of approximately 15 percent and a variable 1 to 3 log10 reduction (average, 95%) in WBC content. The variation in filter WBC removal was related to PRP WBC content and indicated that the filter did not have the capacity for a 3 to 4 log10 removal when PRP WBC content exceeded 1 x 10(8). The in vitro and in vivo measures of platelet quality showed no meaningful differences between filtered and unfiltered PCs by paired t test. The mean differences in posttransfusion percent recoveries and survivals were 0.9 +/- 2.9 percent and 4 +/- 13 hours, respectively. Additional studies were performed using a larger filter with improved capacity. Those studies (n = 18) showed a significant improvement in filtration time and platelet yield and a consistent 3 to 4 log10 reduction in WBCs. Filtration time was 6.6 +/- 2.7 minutes, total PC WBCs were 9.6 +/- 4.6 x 10(4), and total PC platelets were 7.8 +/- 1.8 x 10(10) (mean +/- SD).

Prestorage filtration of PRP and the preparation of filtered platelets do not result in any significant beneficial or adverse effect on subsequent platelet quality. With the large-capacity filter, consistent WBC reduction and good platelet yields are achieved.