White cell apoptosis in platelet concentrates

BACKGROUND: The aim of the present study was the evaluation of the apoptosi s in residual white cells (WBCs) contained in platelet concentrates (PCs) a nd of the relationship of this apoptosis with the concentration of inflamma tory cytokines in the medium and with platelet activation. STUDY DESIGN AND METHODS: Three independent methods were used to evaluated apoptosis in WBCs present in 9 PCs, either from single donors by apheresis (SD-PCs) or from pooled buffy coats (BC-PCs). All PCs were divided in two p arts, one of which was irradiated. PCs were stored up to 4 days at room tem perature, and samples were withdrawn daily for analysis of apoptosis, of pl atelet activation (surface and soluble CD62P), and of cytokine concentratio n (interleukin [IL]-1 alpha, IL-1 beta, IL-6, IL-8, and tumor necrosis fact or alpha). RESULTS: Apoptosis was found to occur with storage in both irradiated and n onirradiated units. Platelet activation increased with storage time and was higher in BC-PCs. The amount of released cytokines was rather variable amo ng PC units. Only IL-8 was consistently found to increase with storage time . CONCLUSIONS: Apoptosis of residual WBCs occurred in PC units as a function of storage time. The amount and the timecourse of apoptosis seem to correla te with IL-8 release rather than with platelet activation or with the occur rence of febrile nonhemolytic transfusion reactions.