Correction of Pseudoreticulocytosis in Leukocytosis Samples Using the Sysmex XE-2100 Analyzer Depends on the Type and Number of White Blood Cells

Abstract

BackgroundThe reticulocyte count is a good marker of erythropoietic activity of the bone marrow. In the mid-1990s, automated flow cytometric analysis replaced microscopy for the quantification of reticulocytes. Leukocytosis cases with an erroneously high reticulocyte count and a high immature reticulocyte fraction (IRF) have been reported. In this study, we analyzed reticulocyte counts in leukocytosis samples, in an effort to identify a correction method.MethodsThe study comprised of 21 samples from 16 leukocytosis patients. Results of reticulocyte analyses obtained using a XE-2100 hematology analyzer (Sysmex, Japan) were compared with those obtained using the supravital staining technique, which is a reference method. If the samples showed erroneously high reticulocyte counts and IRF, they were reanalyzed after serial dilution with isotonic solution.ResultsFive samples from 4 patients showed erroneously elevated reticulocyte counts and/or IRF on the XE-2100 analyzer. They displayed abnormal reticulocyte scattergrams, with 4 of 5 cases indicated by a flag. The white blood cell (WBC) fractions overlapped with the reticulocyte regions, especially with the IRF. Diagnoses and blast counts were variable when such errors occurred; WBC counts varied from 218.19×109/L to 725.14×109/L. The errors were corrected by simple dilution with isotonic solution. However, the corrective WBC counts differed according to individual cases.ConclusionsWhen leukocytosis samples exhibit an abnormal reticulocyte scattergram with a flag, or an abnormally high IRF, we recommend the dilution of the sample with isotonic solution to a WBC count of about 100.00×109/L, followed by reanalysis of the reticulocyte count and reticulocyte scattergram.

Spurious reticulocyte profiles in dogs with large form babesiosis: a retrospective study

“…Other causes for discrepancies between automated and manual reticulocyte analyses include the presence of giant platelets, platelet clumps, abnormal WBC, leukocytosis, and WBC fragments . Heinz bodies, Howell–Jolly bodies, Pappenheimer bodies, or basophilic stippling may also interfere with reticulocyte evaluation by hematology analyzers using flow cytometry .…”

“…In our study, none of these abnormalities were found in dogs with abnormal reticulocyte dot plots and large form babesiosis, and only parasitized RBCs could explain the abnormal profile. Previous studies have shown that in some leukemic human patients and in a leukemic dog, the reticulocyte count was erroneously increased, with an abnormal reticulocyte profile in which the reticulocyte region was completely separated from the RBC region, as observed in some leukemic dogs in this study.…”

A rare case of multicentric eosinophilic granulocytic sarcoma as cause of hindlimb weakness and non‐regenerative anaemia in a minipig

“…A phenomenon called pseudoreticulocytosis is described to occur in samples with leukocytosis when analysed by flow-cytometry-based measures as is the case with the Advia 2120. 35,36 However, the animal did not show leukocytosis or large amounts of eosinophils in the peripheral blood and such interference with cell count is therefore improbable in the presented case. Furthermore, the blood results on day 3 and 6 might have been influenced by the blood transfusions and have to be interpreted with caution.…”

“…The variation in reticulocyte count from day to day, for example, should have been rechecked. A phenomenon called pseudoreticulocytosis is described to occur in samples with leukocytosis when analysed by flow‐cytometry‐based measures as is the case with the Advia 2120 35,36 . However, the animal did not show leukocytosis or large amounts of eosinophils in the peripheral blood and such interference with cell count is therefore improbable in the presented case.…”

Improving reliability of live/dead cell counting through automated image mosaicing

“…In oncology, for example, live and dead cell counting is typically performed to monitor the viability of cancer cells after different chemical [9] or radiobiological treatments [10]. Count accuracy can strongly influence the choice of treatment [11] and also lead to adjustments in the chemotherapeutic protocol [12] and in the drugs dosage administered to the patient [13].…”