Does bacterial contamination of platelet concentrates influence the leucocyte content and the rate of platelet storage lesion?
An observational study was carried out to assess the effect of bacterial growth on changes in platelet cellular indices and leucocyte content. Platelet derived from pooled buffy coats, with and without an additional leucocyte removal step by filtration and platelet derived from Cobe LRS system were used. These were spiked with two doses of several types of bacteria (1 and 50 CFU) in a paired control and test experiment. The changes in cellular parameters were monitored by an automated cell counter (Sysmex SE-9000) and the concentration of the residual leucocyte were evaluated by two automated techniques, based on DNA staining principles (flow cytometry-EPICS-XL Coutter and Imagn 2000). Our results indicate that initially bacterial growth is associated with a decrease in leucocyte count, followed by a concomitant increase in platelet large cell ratio, possibly due to aggregate formation. During the prolonged storage a dramatic increase in pseudoleucocytes was observed by both Imagn 2000 and flow cytometry techniques with an abnormal dot plot around FL3 regions in the latter counting method, making the true identification of native leucocytes rather difficult. It is concluded that bacterial growth is associated with both changes in platelet cellular indices and development of cellular aggregates and/or partially fragmented cells with DNA binding properties appearing as pseudoleucocytes. Further work on the true nature of so called 'pseudoleucocyte' is in progress.
Seghatchian
J
J
National Blood Transfusion Service, London and South East, UK. jerhard.seghatchian@nbs.nhs.uk
Krailadsiri
P
P
Beard
M
M
D001781:Blood Component Removal; D001792:Blood Platelets / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D001793:Blood Preservation / Q000592:standards*; D003257:Consumer Product Safety; D005434:Flow Cytometry; D006801:Humans; D007958:Leukocyte Count; D007962:Leukocytes / Q000378:metabolism / Q000382:microbiology / Q000473:pathology