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July 22, 1983

WBC Differential Counts

Author Affiliations

University of North Carolina School of Medicine Chapel Hill

JAMA. 1983;250(4):483-484. doi:10.1001/jama.1983.03340040027014

To the Editor.—  The editorial (1983; 249:639) and several related articles (1983;249:613 and 1983;249:633) in the Feb 4 issue of The Journal raise some important questions concerning the WBC differential count. The evaluation of the correct use of this test depends to a degree on how it is executed. The manual differential cell count is limited in both precision and accuracy and is particularly poor at recognizing a small number of abnormal cells or evaluating conditions of patients with a low total WBC count.1,2 It works best on "normals." Flow cytometry is a new technology for recognizing cells that is not limited by these shortcomings. At the moment, several manufacturers have flow cytometry systems for the clinical laboratories. The problem of precision is solved by counting greatly increased numbers of cells, and accuracy is based on objective physical measurements rather than subjective morphological findings. The ability to offer simultaneous