Determination of leukocyte counts in cerebrospinal fluid with a disposable plastic hemocytometer.

Manual microscopic cell counting in a Fuchs-Rosenthal (FR) chamber has been the gold standard for quantification of leukocytes in cerebrospinal fluid (CSF). However, for accurate determination of the number and differentiation of cells by chamber counting, hemocytometers must be prepared carefully and kept clean. Improper fitting of the chamber and coverslip changes the volume of sample introduced into the chamber well. Moreover, because conventional hemocytometers are used repeatedly and are breakable, there is a risk of exposure to potentially infectious material. To address these issues, disposable plastic hemocytometers have been developed. However, the accuracy, precision, and clinical usefulness of disposable chambers for CSF cells counting have not been determined. In the present study, we evaluated use of a disposable plastic counting chamber (C-Chip DHC-F01) by comparing its performance with that of an FR chamber for counting of CSF specimens and cell suspensions. Within-run precision of C-Chip counting was comparable or superior to that of FR chamber counting, and excellent correlation between cell counts obtained with the C-Chip chamber and FR chamber was observed. However, C-Chip chambers that were kept at 4 degrees C yielded significantly low cell counts. The disposable hemocytometer will reduce the risk of exposure to potentially infectious material. However, use of C-Chip chambers should be avoided in cold environments.

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/microL (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.