Evaluation of performance of white blood cell reduction filters: An original flow cytometric method for detection and quantification of cell-derived membrane fragments

Background: Contamination of blood products by white blood cells leads to a risk of transmission of infectious agents, particularly abnormal prion pro tein, the probable causative agent of new-variant Creutzfeldt-Jakob disease . Blood product filtration could reduce this risk, but the filtration syste ms might generate potentially infectious membrane fragments. We developed a n original flow cytometric method that allows the detection and quantificat ion of membrane fragments in filtered products and the evaluation of the qu antity of destroyed cells. Methods: This method has four technical requirements: cytofluorometric acqu isition of forward scatter parameters on a log scale, use of a fluorescent aliphatic reporter molecule (PKH26-GL) to identify membrane fragments, quan tification with fluorescent beads, and the drawing up of a standard curve o n the basis of cells destroyed by freezing/thawing to generate cell debris (i.e., quantity of membrane fragments measured versus quantity of destroyed cells). Results and Conclusions: This original method can be used to test new filtr ation devices and it allows optimization of the filtration process or compa rison of different filtration systems. We tested the method with three comm ercial white cell removal filters. We demonstrated that it is possible to e valuate the filter quality, particularly the likelihood of fragment removal during the filtration process. (C) 2001 Wiley-Liss, Inc.