Size referenced electronic leukocyte counting threshold and lysed leukocyte size distribution of common domestic animal species.

This research article investigates the size distribution of leukocytes, or white blood cells, in different types of domestic animals using electronic cell counting and particle size analysis technology. The findings can be used to set an appropriate detection threshold for counting leukocytes in these species, improving accuracy of cell count and reducing errors caused by debris.

Methodology

• The research used a single channel electronic cell counter coupled with a particle size analyzer to determine leukocyte size distribution in the blood of four domestic animal species: dogs, cats, horses, and cows.
• The blood samples were diluted with a chloride-based diluent and treated with a conventional stromatolysin, a substance used to break open (lyse) cells.

Findings

• The histograms generated by the particle size analyzer, which depict the distribution of leukocyte sizes, were typically unimodal, featuring a single peak. However, some histograms had two peaks, indicating bimodal size distribution.
• The researchers found the mean volumes for the lysed leukocyte particles were 49.2 fl (dogs), 51.1 fl (cats), 55.4 fl (horses), and 65.0 fl (cows).
• By examining these histograms, the researchers established a lower threshold of 30 fl, referenced to latex spheres, to count leukocytes for these four species simultaneously.
• Debris found in many samples often sat below this threshold, separated from the leukocyte population by a valley on the histogram.

Threshold Failures and Recommendations

• The study noted instances of ‘threshold failure’, where debris extended significantly into the leukocyte size range, occurring in 9% of dog and cat samples, and 7% of cow samples.
• Consequently, the researchers recommend careful establishment of the lower counting threshold to minimize both the frequency and severity of leukocyte count errors associated with failure to exclude debris.