Automated enumeration of reticulocytes using acridine orange

Manual methods of counting reticulocytes using supravital stains, such as new methylene blue, have long been recognized to be subject to technical errors. Automated reticulocyte enumeration has recently become available with the development of an automated cell flow-cytometer, the Ortho Spectrum III. In this method a fluorescent dye, acridine orange, which stains RNA in a manner similar to supravital stains, is used to distinguish reticulocytes from mature erythrocytes. We have evaluated this technique and found that it compares favourably with manual counting methods.