Multicenter flow cytometry proficiency testing of canine blood and lymph node samples

Area of Science:

• Veterinary Hematology
• Immunophenotyping
• Diagnostic Cytology

Background:

• Flow cytometry (FC) is increasingly utilized in veterinary medicine for hematolymphoid cell characterization.
• Limited guidelines exist for optimizing FC assays and interpreting results in veterinary diagnostics.
• Inter-laboratory concordance of FC findings in veterinary samples is largely unknown.

Purpose of the Study:

• To assess inter-investigator agreement on flow cytometry (FC) results from split samples analyzed across different veterinary laboratories.
• To evaluate agreement on the interpretation of archived flow cytometry standard (FCS) data files.
• To identify variability in FC interpretation for veterinary hematolymphoid cell analysis.

Main Methods:

• A multicenter observational cross-sectional study involving nine client-owned dogs' samples (blood/lymph node aspirates).
• Samples were analyzed using diverse laboratory-developed protocols, cytometers, and software.
• Archived FCS data files from 11 additional dogs were interpreted by participating investigators.

Main Results:

• Overall agreement on FC sample interpretation was strong (κ = 0.86).
• Agreement varied by category, ranging from moderate to perfect for fresh samples.
• Interpretation agreement for lymphoproliferation or leukocyte categories from FCS files was weaker (κ = 0.58).

Conclusions:

• Flow cytometry effectively identifies lymphoproliferations in veterinary samples.
• Consistent identification of hematolymphoid neoplasia categories was variable across fresh samples and archived files.
• Standardization of flow cytometry protocols and interpretation is crucial for veterinary diagnostics.