Short preheating at 41°C leads to a red blood cells count comparable to that in RET channel of Sysmex analysers in samples showing cold agglutination

Optimizing the management of analytical interferences affecting red blood cells on XN-10 (Sysmex®)

INTRODUCTION

Interferences on red blood cells (RBCs) measurement and the associated parameters in haematology analyzers are very common. Many sources of interferences are described but their management remains uncertain depending on the measurement system; we aimed at developing an optimized scheme allowing the accurate management of most interferences affecting RBCs, based on the alternative "optical" parameters from SYSMEX XN-10.

METHODS

Samples from 12 groups of relevant interferences were analysed and compared with a control group allowing (1) the determination of deviation thresholds beyond which an interference is likely, and (2) the development of two flowcharts for their subsequent management. These flowcharts were then evaluated among a bank of retrospective typical cases of interferences and in the routine flow of the laboratory.

RESULTS

After verifying the excellent agreement between standard and alternative parameters, the comparative study between analytical channels allowed to determine an acceptable deviation and then discriminate technical concerns caused by cold agglutinins, leukocytosis and plasma-related interferences. This led to the development of flowcharts ensuring the accurate management of these interferences, whether MCHC is <320 or >365 g/L. These proposed flowcharts allowed the correction of 63/65 historical confirmed interferences cases (97%). Furthermore, they corrected 18 results among 901 unselected prospective samples.

CONCLUSION

The resulting flowcharts allow a relevant correction for most common interferences affecting RBCs and are now definitively included in the routine analytical management and will be directly incorporated in the middleware of the laboratory.

Use of the reticulocyte channel warmed to 41°C of the XN-9000 analyzer in samples with the presence of cold agglutinins

OBJECTIVES

The purpose of this study was to compare data obtained from the reticulocyte channel (RET channel) heated to 41°C with those obtained from impedance channel (I-Channel) at room temperature in the samples with the mean corpuscular hemoglobin concentration (MCHC)<370g/L and in samples with the MCHC>370g/L, in the presence of cold agglutinins.

METHODS

In this study, 60 blood samples (group 1) with the MCHC<370g/L (without cold agglutinins) and 78 blood samples (group 2) with the MCHC>370g/L (with cold agglutinins) were used to compare the two analytical channels of the XN-9000 analyzer in different preanalytical conditions. The parameters evaluated in both groups were the following: red blood cell (RBC), hemoglobin (HGB), hematocrit (HCT), mean cell volume (MCV), RBC-most frequent volume (R-MFV), mean hemoglobin concentration (MCH) and mean cellular hemoglobin concentration (MCHC).

RESULTS

The results of this study showed an excellent correlation with both channels of the XN-9000 analyzer in samples with and without cold agglutinins, except for the MCHC. The bias between the values obtained in the I-channel and those obtained in the RET channel of both groups was insignificant and remained within the limits of acceptability, as reported by Ricos et al. for all considered parameters, except for MCHC.

CONCLUSIONS

The presence of cold agglutinins in blood samples can be detected by a spurious lowering of the RBC count and by a spurious increase in the MCHC. The RET channel represents a great opportunity to correct the RBC count in a rapid manner without preheating. However, neither methodology can completely solve the residual presence of cold agglutinins in all samples, despite the MCHC values being < 370g/L.

Cold agglutinin disease: current challenges and future prospects

Cold agglutinin disease (CAD) is a complement-dependent, classical pathway-mediated immune hemolytic disease, accounting for 15–25% of autoimmune hemolytic anemia, and at the same time, a distinct clonal B-cell lymphoproliferative disorder of the bone marrow. The disease burden is often high, but not all patients require pharmacological treatment. Several therapies directed at the pathogenic B-cells are now available. Rituximab plus bendamustine or rituximab monotherapy should be considered first-line treatment, depending on individual patient characteristics. Novel treatment options that target the classical complement pathway are under development and appear very promising, and the C1s inhibitor sutimlimab is currently being investigated in two clinical Phase II and III trials. These achievements have raised new challenges and further prospects, which are discussed. Patients with CAD requiring therapy should be considered for clinical trials.