Differential Leukocyte Counting: Evaluation of Four Methods

DIFFERENTIAL LEUKOCYTE COUNTING: EVALUATION OF FOUR METHODS. H. Tvedten, I. Lillieho¨o¨ k. Swedish University of Agricultural Sciences SLU, University Veterinary Hospital Laboratory, Uppsala, Sweden. A new method for determining the differential leukocyte count is the CellaVision TM DM96 (CV DM96). This is a mechanical photomicroscope and software system that photographs and pre-classifies leukocytes in a blood smear. It has software that allows comparison of large and variable numbers of excellent photos of cells displayed on a computer screen. The final classification by the operator is by easy transfer of cells to their proper classification with a computer mouse. Evaluation of this instrument for veterinary use was done by comparing its performance with over 100 canine blood samples to manual differential leukocyte counts, Advia 2120 automated differential leukocyte counts and Sysmex XT 2000 iV automated differential leukocyte counts. Precision studies were also performed on 2 blood samples analyzed 10 times by each method. Final data and evaluations were not available before the deadline for submission of this abstract, but collection of raw data has been completed. Preliminary evaluation indicates the automated differential leukocyte counts of the Advia and Sysmex have better precision (CV , 2%) for neutrophil and lymphocyte counts than manual or CV DM96 counts (%) for these cell types. Automated counts, however, did not include non-segmented neutrophil, atypical lymphocyte or accurate basophil counts. All methods had high imprecision (CV . 25%) for uncommon cell types like bands, basophils, LUC (Advia’s large unstained cells) and even eosinophils, monocytes and lymphocytes when they were in small numbers. (Reprinted with permission from Vet Clin Pathol, 38 [supplement], 2009, http://www. blackwellpublishing.com/vcp)