LOW RETENTION OF WHITE CELL FRAGMENTS BY POLYESTER FIBER WHITE CELL-REDUCTION PLATELET FILTERS

Background: There is intense interest in the potential of current white cell (WBC)reduction filters to prevent the alloimmunization of patients by the residual donor WBCs in filtered blood components transfused to them. Little attention has been paid to the capacity of current synthetic fiber filters to remove WBC membrane fragments bearing detectable leukocyte antigens. Study Design and Methods: Fluorescein isothiocyanate-conjugated monoclonal antibody to a universal WBC membrane antigen (CD45) and high-speed centrifugation coupled with ficoll-hypapue differential sedimentation were used to quantitate low-density WBC fragments In single-donor platelet components before and after filtration to determine if a polyester fiber filter retained WBC fragments. Results: Prefiltration measurements in 25 single-donor platelet components indicated that WBC fragments increased with length of storage up to 5 days at room temperature (p<0.0001). When fragments in eight components were measured before and after filtration, absolute values for differences were insignificant (p = 0.15). Conclusion: WBC fragments were poorly retained by these polyester fiber WBC-reduction filters. The antigenicity of WBC fragments could contribute to the WBC alloimmunization of some recipients of WBC-reduced blood components.