Phosphatidylserine exposure in platelet concentrates during the storage period: differences between the platelets collected with different cell separators M. Lai * ,C.Rumi,G.DÕOnofrio, P.L. Puggioni, G. Menichella, A. Candido, G. Leone Immunohematology Laboratory, Chair of Hematology, Transfusion Center, Catholic University of Sacred Heart, Largo Gemelli 8, Roma 00168, Italy Received 17 March 2002; accepted 19 July 2002 Abstract Background and objectives: Plateletalterationsoccurduringtheproductionandstorageofplateletconcentrates,the so called ‘‘storage lesion’’. We studied the platelet alterations during the storage period in apheresis concentrates, employing flow cytometry for phosphatidylserine (PS) detection on platelets during the five days of storage. Material and methods: Twenty-seven single donor platelet concentrates harvested with the Cobe Trima, Baxter Amicus,orHaemoneticsMCSþ wereanalyzedforPSexposurebyflowcytometryonthedayofproduction(day1)and on days 3 and 5 of storage. Furthermore PS expression was analyzed in platelet donorsÕ blood samples withdrawn before plateletpheresis. Results: PSexpressiononplateletsgavethefollowingmedianvalues:inblooddonorsbeforeapheresisitwas1.12% (0:13–1:78) in platelets concentrates on the first day (2 h after apheresis) 2.06% (0:66–15:2), the third day 6.57% (1:98–51:13) and the fifth day 23.04% (3:86–80:23). All differences between median values of PS expression in blood samples before apheresis, and platelets concentrates on days 1, 3 and 5 of storage, are statistically significant. The expression of PS in platelet concentrates was analyzed in relation to the blood cell separator used for the collection procedure and showed the following results: on day 1 the median values of PS in platelet concentrates collected with the three different blood cell separators, Trima, Cobe and MCS, did not show statistically significant differences. On day 3, the platelets concentrates collected with the Trima and with the MCS showed differences that were statistically significant. Those were respectively 10.59% (4:56–51:13) and 3.53% (1:98–12:61), p ¼ 0:005. The PS expression in platelet concentrates collected with the Trima and MCS showed differences that are also statistically significant on day 5 at respectively 32.4% (9:61–80:23) and 8.57% (3:86–48:42), p ¼ 0:005. Conclusions: PSexposureinplateletconcentratesondays3and5risetolevelsthatcouldcompromisethequalityof theplateletunits.Improvementsinstandardizedplateletqualitycontrols,andinplateletcollectionsystemsarerequired to reduce the storage lesions in platelets concentrates. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Platelet lesions; Storage lesions; Phosphatidylserine; Annexin V; Platelet storage www.elsevier.com/locate/transci Transfusion and Apheresis Science 27 (2002) 239–245 * Corresponding author. Tel./fax: +39-06-35511015. E-mail address: mlai@rm.unicatt.it (M. Lai). 1473-0502/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S1473-0502(02)00071-X