Performance evaluation of high fluorescence lymphocyte count: Comparability to atypical lymphocyte count and clinical significance

Objectives: To investigate the association between high-fluorescence lymphocyte cell (HFLC) and atypical lymphocyte (AL) counts, and to determine the clinical significance of HFLC. Methods: We compared automated HFLC and microscopic AL counts and analyzed the findings. Patient clinical data for each specimen were reviewed. Results: A total of 320 blood specimens were included. The correlation between HFLC and microscopic AL counts was 0.865 and 0.893 for absolute and percentage counts, respectively. Sensitivity, specificity, and accuracy of HFLC at the cutoff value of 0.1 × 10⁹ per L for detection of AL were 0.8, 0.77, and 0.8, respectively. Studied patients were classified into 4 groups: infection, immunological disorders, malignant neoplasms, and others. Patients with infections had the highest HFLC. Most of those patients (67.7%) had dengue infection. Conclusion: HFLC counts were well-correlated with AL counts with the acceptable test characteristics. Applying HFLC flagging may alert laboratory staff to be aware of ALs.