Automated hematology analyzers (analyzers) can provide complete blood counts and white blood cell (WBC) differentials in clinical laboratories
and alert users to the presence of quantitative and qualitative cell abnormalities through cautionary flags. In this study, we applied analyzers to the screening of apoptotic cells in peripheral blood and examined the triggering capacity of cautionary flags to detect apoptotic cell populations. EDTA-anticoagulated fresh peripheral blood from patients with acute infectious mononucleosis containing atypical lymphocytes comprising 12.3 Ψ 4.0% of WBC was applied to a Beckman-Coulter MAXM A/L Retic (MAXM) analyzer. The lymphocyte cluster spread upward in VOLUME/DF1 scattergrams and the threshold lines between lymphocyte and monocyte clusters shifted upward. Flags for the number and percentage of lymphocytes, variant lymphocytes, and blast cells were generally present for samples containing atypical lymphocytes. After the blood from acute infectious mononucleosis patients was incubated for 4 h at 37Β°C, peripheral blood smears revealed the presence of morphologically apoptotic cells comprising 9.0 Ψ 4.2% of WBC and a comparable reduction of lymphocytes. On the MAXM analyzer, the apoptotic lymphocyte cluster appeared under the lymphocyte cluster in VOLUME/DF1 scattergrams. However, no specific flag was present to alert users to the presence of the apoptotic lymphocyte cluster. We conclude that visual inspection of scattergrams generated by the MAXM analyzer can be useful for the detection of apoptotic lymphocytes in peripheral blood. Cytometry (Comm. Clin. Cytometry) 42:209 -214, 2000. Published 2000 Wiley-Liss, Inc. β
Key terms: automated hematology analyzer; apoptosis; flag; MAXM; infectious mononucleosis
Recent improvements in automated hematology analyzers (analyzers) have permitted accurate determinations of blood cell counts and white blood cell (WBC) differentials (1). Measurement of electric impedance, laser light scatter, conductivity, and cytochemistry combined with the use of cell-specific lysing reagents have provided the tools for automated assessment of WBC differentials. Different instruments can detect the presence of abnormal cell populations and provide two types of semi-interpretative cautionary flags. Definitive flags are designed to detect quantitative abnormalities whereas suspect flags are designed to detect qualitative abnormalities. These flags are critical for screening cases that require microscopic review or manual differentials.
Apoptosis or programmed cell death plays a key role in many physiological processes including embryonic tissue development, immune cell maturation, and maintenance of adult tissue architecture (2). Defective regulation of apoptosis can lead or contribute to disease (e.g., AIDS, autoimmune diseases, degenerative dis-