Urine flow cytometer quantification of leukocytes in samples containing a large proportion of lymphocytes

Objective: We compared leukocyte counts obtained by cytometric analysis and Fuchs–Rosenthal (FR) chamber counting in different proportions of lymphocytes (Lym%) suspensions and cerebrospinal fluid (CSF). Design and methods: UF-100 (UF) was evaluated. For preparation of cell suspensions, gradient density centrifugation method was used. Results: The regression equation for UF and FR chamber counting of the cell suspensions was y = 0.88x + 18.8 WBC/μL (r = 0.832, n = 106). For a few high Lym% samples, markedly underestimated WBC counts were obtained by UF. Conclusions: Underestimated WBC count is due not to systematic error but to random error. Counts of the “other” population by UF may be useful for detection of underestimated samples.