Correlation between the cell population in the automated hematology analyzer high‐fluorescence region and atypical lymphocyte flags

During routine blood measurements using an automated hematology analyzer, two easily confused types of suspect flags related to lymphocytes often appear: atypical and immature lymphocytes. The aim of this study was to investigate the correlation of high fluorescence cell ( HFC ) parameter and lymphocyte flags determined from an automated hematology analyzer. Methods A total of 93 patients affected by various pathologic conditions (viral infection, immunological disease, oncological disease and tumor) were divided into an “atypical lymphocytes” group (“atypical” for short), an “immature lymphocytes/blasts” flag group (abnormal), a mixed‐flag group that includes “atypical lymphocytes” (mixed), and a non‐flag group (non‐flag). Results The numbers of HFC s in the atypical, abnormal, mixed, and non‐flag groups were 1.8% (0.9%‐5.5%), 0.7% (0.1%‐5.0%), 2.3% (1.2%‐5.0%), and 0.8% (0.7%‐1.2%), respectively. The HFC s of “atypical” appeared as a separate cluster with clear boundaries. The HFC s of “abnormal” as an unclear boundaries, and it was difficult to accurately distinguish between the HFC s from the immature lymphocytes and the normal lymphocytes. The lower limit of HFC when the atypical lymphocyte flag appeared was 0.04 × 10 9 /L. The number of HFC s was similar to atypical lymphocytes detected by microscopy and CD19 + CD20 − CD27 ++ cells by flow cytometry at 78% and 76%, respectively. The number of HFC s detected in “atypical” and CD19 + CD20 − CD27 ++ cells showed good consistency ( r  = .715), whereas the consistency was poorest for “abnormal” ( r  = .176). Conclusion It demonstrates that HFC s reflects atypical lymphocytes better than immature lymphocytes/blasts.