Can Immature Granulocyte Counting be Utilized in the Selection of Samples for Flow Cytometric Enumeration of Stem Cells?

ABSTRACT

BACKGROUND: This study aimed to compare the IMG counting by an auto hematology analyzer with the flow cytometric enumeration of CD34+ cells. METHODS: All data from 124 samples submitted to the hematology laboratory for CD34+ cell counting in 2019 and 2020 were retrospectively evaluated. Whole blood samples were taken into EDTA tubes and assayed within 2 hours. The numbers and percentages of WBC and IMG were determined by using Mindray BC6200 hematology analyzer, while the same were determined for CD45 and CD34+ cells by using Beckman Coulter Navios flow cytometer. The performance of the new method was determined by the receiver operating characteristic (ROC) analysis. RESULTS: Out of the 124 samples, 94 were collected from healthy individuals and 30 were collected from patients. A significant correlation was found between IMG and CD34+ cell counts in all patients (r = 0.71, p = 0.000) at the cutoff values of > 20/µL and > 50/µL. The Bland-Altman analysis of all patients showed that there was an agreement between the two methods. When the cutoff value of 20/µL for CD34+ cells was used in the ROC analysis, the sensitivity and specificity were calculated as 100 (96.1 - 100) and 96.77 (83.3 - 99.9), respectively, for the IMG count of > 900/µL. CONCLUSIONS: An IMG count of 900/µL can be used as the cutoff value in the analysis with the Mindray BC6200. The IMG counting cannot replace the flow cytometric CD34+ cell enumeration but can be used in the selection of the samples for stem cell enumeration by flow cytometry.