Contamination rate of white blood cells in fresh frozen plasma and evaluation of a commercial WBC-reduction filter

Kim, Dong Lyul; Kim, Duck An

Abstract

BACKGROUND
Recently, sufficient numbers of lymphocytes that may cause alloimmunization have been detected in fresh frozen plasma (FFP) and the need for filtration and/or irradiation of FFP for certain patients has been proposed. We examined the numbers of white blood cells (WBCs) in FFP and evaluated a new WBC-reduction filter designed for FFP.
METHODS
A total of 118 units of FFP were analyzed. We counted WBCs by using the crystal violet-staining method. Forty-four units of FFP were tested for WBC numbers before and after filtration by using the Nageotte chamber. The viable WBC count was performed using the 0.4% trypan blue-staining method. The biologic activity of the coagulation factor viii was measured in 34 units of FFP before and after filtration with the ACL 3000 (Instrumentation Laboratory, Milano, Italy).
RESULTS
In the 118 units of FFP, 39 units (33.1%) and 1 unit (0.9%) had counts greater than 1X10(6)/unit and 5X10(6)/unit, respectively. The filter reduced the WBC numbers to less than 1X106/unit in all units. The average percentage of viable WBCs before and after filtration was 34.9% and 4.7%, respectively. The average leukocyte removal rate of the WBC-reduction filter was 81.0%. The average factor viii activity before and after filtration was 72.2 U/dL and 75.1 U/dL, respectively.
CONCLUSIONS
Some FFP prepared by the Korean Red Cross blood center may contain enough to require WBC-reduction filtration. Therefore, WBC-reduction filtration of FFP should be considered in order to prevent adverse effects, particularly in those patients expected to receive repeated transfusions.