Evaluation of urine dipsticks for quality control of residual erythrocytes and leukocytes in leukocyte-depleted donor plasma

Currently used methodologies for quality control of residual leukocytes and erythrocytes in leukocyte-depleted plasma are either expensive or time-consuming. It has been proposed that urine dipsticks could be used as a screening method for residual erythrocytes. The aim was, therefore, to evaluate if urine dipsticks could be used to detect residual erythrocytes and also residual leukocytes in leukocyte-depleted plasma. Dilution series ranging over the decision limits for residual erythrocytes and leukocytes were prepared. Positive, negative and overall agreements, as well as the precision and joint frequency distributions, were calculated for five dipstick analyzers and their corresponding dipsticks. Twenty-four consecutive leukocyte-depleted donor plasma samples were also tested. None of the dipstick analyzers had both a high positive and a high negative agreement. Accordingly, none of the analyzers were able to discriminate between cell concentrations close to the decision limits. The inconsistency count revealed differences in precision between the dipstick analyzers. In the 24 consecutive donor samples, no significant correlation between the dipstick analyzers and the reference methods were found. In conclusion, urine dipsticks are not suitable for quality control of residual leukocytes and erythrocytes in leukocyte-depleted donor plasma.

Evaluation of a routine hematology analyzer for quality control of leukoreduced plasma

BACKGROUND

Quality control of residual white blood cells (WBCs) and red blood cells (RBCs) in leukoreduced plasma is mandatory. Although technological advances have been made, analysis of quality controls using routine hematology analyzers has not generally been introduced. The aim of this study was to evaluate if the routine hematology analyzer Sysmex XN-10, (Sysmex Nordic ApS) could be used for quality control of residual WBCs and RBCs in leukoreduced plasma.

STUDY DESIGN AND METHODS

Linearity, accuracy, and precision were established for two Sysmex XN-10 analyzers using spiked donor plasma. ADAM rWBC (NanoEnTek) and manual counting in the Bürker chamber (NanoEnTek) were reference methods for WBCs and RBCs, respectively. Twenty-five consecutive leukoreduced donor plasma samples were also tested.

RESULTS

For WBCs, the linearity criteria were met for the ADAM rWBC, but not for the Sysmex XN-10 instruments. Precision on both Sysmex XN-10 instruments was accurate only at 6 cells/μL, and accuracy was consistently acceptable only at 5 to 6 cells/μL. The precision and accuracy of the ADAM rWBC were acceptable at 2 to 6 cells/μL. For RBCs, both Sysmex XN-10 instruments and manual counting in the Bürker chamber were linear and fulfilled the precision criteria. Accuracy was acceptable for both Sysmex instruments at 6 to 12 × 10⁹ WBCs/L but fluctuated within the study's measuring range for the Bürker chamber. No false-positive results were seen in the 25 consecutive donor plasma samples tested.

CONCLUSION

For quality control purposes of leukoreduced plasma, the Sysmex XN-10 analyzer is suitable for the enumeration of residual RBCs but not of residual WBCs.

Genome-wide platelet RNA profiling in clinical samples

Human blood platelets are anucleate cells that contain minute amounts of translational active mRNA. Investigation of the gene expression profile by microarray analysis has become an excellent tool for better understanding of normal and pathological platelet function. Its use, however, is often limited by the low yield of megakaryocytic-derived mRNA, the possible contamination with leukocytes during platelet preparation and the small platelet volume in clinical settings, especially in pediatric patients. In this chapter, we present a protocol for the isolation of leukocyte-depleted platelet samples in clinical settings and an optimized procedure for transcript profiling, using the Agilent oligo microarray technology. In particular, we discuss the special aspects of platelet purification when working with blood sample volumes not exceeding 3-5 ml, which is typical in pediatric patients and we furthermore provide detailed information for transcript profiling of extremely small amounts of platelet RNA.