Utility of flow cytometric reticulocyte quantification as a predictor of engraftment in autologous bone marrow transplantation

Abstract

Flow cytometric reticulocyte quantification with thiazole orange (TO) was used to study erythropoiesis in 20 patients following autologous bone marrow transplantation for the treatment of acute myelogenous leukemia. Flow cytometric reticulocyte analysis provided not only the reticulocyte percentage and absolute reticulocyte count but a quantitative reticulocyte maturity index (RMI) proportional to the amount of RNA in the reticulocytes. The RMI values, but not the reticulocyte percentage or absolute counts, correlated temporally with the rise in the absolute neutrophil counts in the posttransplantation period. In the majority of patients (12/20), the RMI value was the earliest indicator of bone marrow engraftment. The findings of this study demonstrate an important clinical utility of TO reticulocyte analysis by flow cytometry and indicate the diagnostic importance of the RMI measurement in the evaluation of erythropoietic activity in bone marrow transplant patients.

Recovery from neutropenia can be predicted by the immature reticulocyte fraction several days before neutrophil recovery in autologous stem cell transplant recipients

“…8,9 The fluorescence intensity of the entire reticulocyte population was initially reported as the reticulocyte maturation index or the mean fluorescent index. 10,11 Reticulocytes have now been grouped into low, middle (MFR) or high fluorescent region (HFR) corresponding to the lower, middle and higher RNA content, respectively. The immature reticulocyte fraction (IRF) measures the MFR and HFR populations and is more reproducible than the HFR.…”

Proposal for standardization of flow cytometric reticulocyte maturity index (RMI) measurements

“…A subcommittee of the National Committee for Clinical Laboratory Standards is developing guidelines for this form of clinical testing. The American Medical Association CPT coding system now recognizes reticulocyte analysis by flow cytometry as a diagnostic medical test, distinct from manual microscopic counting methodology.FCM retic can be performed with a number of methods [10,25], utilizing fluorescent dyes such as thiazole orange [4,8,9,12,17], thioflavin T [5,19,21], ethidium bromide [51, pyronin Y [24,271, and acridine orange [10,19,22,23,33-351. In addition, TOA Medical Electronics (Kobe, Japan) markets a dedicated, semiautomated reticulocyte counter using flow cytometric technology and the fluorescent dye auramine 0 on the Sysmex R-1000 instrument [16,28,291.…”

“…FCM retic can be performed with a number of methods [10,25], utilizing fluorescent dyes such as thiazole orange [4,8,9,12,17], thioflavin T [5,19,21], ethidium bromide [51, pyronin Y [24,271, and acridine orange [10,19,22,23,33-351. In addition, TOA Medical Electronics (Kobe, Japan) markets a dedicated, semiautomated reticulocyte counter using flow cytometric technology and the fluorescent dye auramine 0 on the Sysmex R-1000 instrument [16,28,291.…”

“…FCM retic can be performed with a number of methods [10,25], utilizing fluorescent dyes such as thiazole orange [4,8,9,12,17], thioflavin T [5,19,21], ethidium bromide [51, pyronin Y [24,271, and acridine orange [10,19,22,23,. In addition, TOA Medical Electronics (Kobe, Japan) markets a dedicated, semiautomated reticulocyte counter using flow cytometric tech- Laboratory methods of quality control of clinical FCM retic analysis have been proposed using refrigerated rabbit blood [5,61, normal human samples [9,10,3 11, and commercial reticulocyte control reagents (Streck Laboratories, Omaha, NB).…”

“…The Sysmex R-1000 provides a fractionation of reticulocyte into 3 regions of low, medium, and high fluorescence intensity based upon auramine 0 staining, which can be manipulated to create a clinically useful RMI [30]. Our group and Wells et al have reported clinical utility using mean arbitrary fluorescent channel units (AFU) of thiazole orange (TO) stained reticulocytes to quantify an RMI parameter [1,[8][9][10]361. Although all these methods provide reproducible means to generate an RMI parameter, the units of RMI expression are not transferable between different staining procedures or even between laboratories using the same FCM retic method.…”