WBC subset analysis of WBC-reduced platelet components

BACKGROUND: WBC-reduced platelet components may be prepared by filtration o r apheresis processing. Both methods have previously been shown to result i n a residual total WBC content <5 x 10(6) per component. However, there may be differences in the efficacy of these techniques for removing certain WB C subsets. STUDY DESIGN AND METHODS: Two multiparameter flow cytometric assays were de veloped and validated to perform WBC analysis on WBC-reduced platelets coll ected with two apheresis instruments (Amicus and COBE Spectra) and on 6 uni ts of filtered pooled random-donor platelet concentrates. RESULTS: All components contained <1 x 10(5) WBCs. The COBE Spectra and Ami cus apheresis platelet components contained more WBCs than did filtered poo led platelets (p<0.05). Lymphocytes (T and B), monocytes, and granulocytes were identified in all components. Granulocyte content was lowest in the Am icus components and filtered pools. Monocytes were lowest in filtered pools . Amicus platelet components had fewer granulocytes and monocytes than the COBE Spectra platelets. Amicus and COBE Spectra components contained more l ymphocytes than the filtered pools. CONCLUSION: Multiparameter flow cytometry can be used to quantify and chara cterize WBCs in WBC-reduced platelet components. WBC reduction by filtratio n or apheresis was highly effective. WBCs from each subset were identified in all components. Although filtered pools had the lowest numbers of WBCs, the very low numbers observed in all components suggests that the absolute quantitative differences in WBC subset content are of questionable clinical significance.