Periodic alternating interface positioning to lower WBC contamination of apheresis platelet concentrates: a multicenter evaluation.

Background: A new software version of a cell separator (AS TEC 204, Fresenius) providing WBC-reduced single-donor plateletpheresis concentrates was tested.

Study Design And Methods: Dual-needle apheresis procedures (n = 621) were performed in three centers, using either fixed interface positioning (FIP) or periodic alternating interface positioning (PAIP). The other separation parameters (e.g., anticoagulant:whole-blood ratio, and blood flow) were set individually. All platelet concentrates were evaluated for platelet yields and contaminating WBCs.

Results: The introduction of the PAIP resulted in a significant (p<0.001) reduction in contaminating WBCs (median, 30,000) from the numbers seen with FIP (median, 2,300,000) while maintaining the separation efficacy (47%) and separation time. Ninety-eight percent of all concentrates contained less than 5 x 10(6) WBCs per concentrate and 92 percent contained less than 1 x 10(6).

Conclusion: Plateletpheresis using the AS TEC 204 cell separator with PAIP is a valid alternative to WBC reduction by filtration. It may provide WBC-reduced platelet concentrates without the additional cost of filters. However, the reliability of the WBC reduction is not yet advanced enough that PAIP can be employed without any monitoring of the end product.