Residual red cell and platelet content in WBC-reduced plasma measured by anovel flow cytometric method

Background: The levels of residual red blood cells (RBC) and platelets (PLT ) in WBC-reduced plasma are often below the lower detection limit of automa ted blood cell counters. This study established a novel flow cytometric met hod for the enumeration of residual RBC and PLT in plasma. Furthermore, the ir levels in WBC-reduced plasma prepared by using various filters were inve stigated. Materials anti methods: WBC-reduced plasma was prepared from two sources: ( i) filtration or buffy-coat reduced plasma using dock-on Baxter, Pall and M aco Pharma plasma filters; (ii) filtered whole blood using integral Asahi R Z2000, Maco Pharma LST1, NPBI, and Pall WBF2 whole blood filters. Residual RBC and PLT counts were assessed by using a TruCount tube (Becton Dickinson ) containing a known number of lyophilized fluorescent beads. RBC and PLT w ere labelled with dual monoclonal antibodies, anti-CD41-R-phycoerythrin and anti-glycophorin A-fluorescein isothiocyanide, and analyzed by flow cytome ter. Results: The flow cytometric method used in this method can detect residual RBC, PLT as well as RBC-MV simultaneously. The sensitivity of the assay wa s 50 x 10(6) cells/l with the coefficient of variations less than or equal to 10%, Baxter and Maco Pharma plasma filters consistently reduced both RBC , RBC-MV and PLT to below 50 x 10(6)/l. Plasma derived from day 1 RZ2000 fi ltered whole blood contained PLT below 50 x 10(6) cells/l, whereas day 0 NP BI filtered whole blood showed the highest level of residual PLT. Conclusion: A sensitive and accurate method for the detection of low levels RBC, RBC-MV, and PLT was established to measure their levels in WBC-reduce d plasma. The procedure is simple and practical for routine quality monitor ing of plasma, as well as for setting a new specification for WBC-reduced p lasma. (C) 2001 Elsevier Science Ltd. All rights reserved.