Time dependent increase of differential monocyte count on the Sysmex NE-8000

During storage of whole blood samples the results of white blood cell counts on a Sysmex NE-8000 Hematology Analyser showed an apparent shift from the granulocytes towards monocytes. The effects of various storage conditions were investigated by incubating blood samples at different temperatures and time intervals. Granulocyte activation and degranulation during storage resulted in a false elevation of the automated monocyte differential counts. The phenomenon occurs at temperatures beyond ambient room temperature.