FLOW CYTOMETRIC ANALYSIS OF RETICULOCYTES USING AN RNA-BINDING FLUOROCHROME

The reticulocyte count is an important parameter in the diagnosis of a naemia. The commonly used microscopic counting technique is, however, laborious and hampered by poor precision and low sensitivity. An alter native method has recently been developed, which is based on flow cyto metric identification and quantification of reticulocytes after staini ng with an RNA-binding fluorochrome, thiazol orange. The two methods w ere compared both in a sample of healthy individuals and in patient sp ecimens. The correlation between the methods was good, but the flow cy tometric analysis consistently gave values approximately 1.5 times hig her (reticulocytes in per cent of erythrocytes) than the microscopic t echnique. The coefficient of variation was significantly lower for the flow cytometric technique. Reference values for the reticulocyte coun t were determined and the effects of storage of specimens were evaluat ed. It is concluded that flow cytometric analysis of reticulocytes is more sensitive and has a better precision that the standard microscopi c procedure.