Enumeration of residual white blood cells in leukoreduced blood products: Comparing flow cytometry with a portable microscopic cell counter

Transfusion of blood components is potentially associated to the risk of cell-mediated adverse events and current guidelines require a reduction of residual white blood cells (rWBC) below 1 × 106 WBC/unit. The reference method to enumerate rare events is the flow cytometry (FCM). The ADAM-rWBC microscopic cell counter has been proposed as an alternative: it measures leukocytes after their staining with propidium iodide. We have tested the Adam-rWBC for the ability to enumerate rWBC in red blood cells and concentrates.We have validated the flow cytometry (FCM) for linearity, precision accuracy and robustness and then the ADAM-rWBC results have been compared with the FCM.Our data confirm the linearity, accuracy, precision and robustness of the FCM. The ADAM-rWBC has revealed an adequate precision and accuracy.Even if the Bland–Altman analysis of the paired data has indicated that the two systems are comparable, it should be noted that the rWBC values obtained by the ADAM-rWBC were significantly higher compared to FCM. In conclusion, the Adam-rWBC cell counter could represent an alternative where FCM technology expertise is not available, even if the risk that borderline products could be misclassified exists.