A new flow cytometric method for differential cell counting in ascitic fluid

Area of Science:

• Clinical diagnostics
• Biomedical engineering
• Fluid analysis

Background:

• Cell counting in body fluids like ascites is challenging and time-consuming.
• Current methods involve automated counters or manual counting chambers with cytospins, possessing several limitations.
• A novel flow cytometry assay was developed for rapid ascites cell enumeration.

Purpose of the Study:

• To develop and validate a flow cytometry assay for accurate cell counting in ascitic fluid.
• To compare the performance of the flow cytometry assay against an automated cell counter (LH750) and manual cytospin analysis.
• To assess the utility of flow cytometry for detecting spontaneous bacterial peritonitis (SBP) based on polymorphonuclear neutrophil (PMN) counts.

Main Methods:

• Fifty-three ascitic fluid samples from 38 patients were analyzed.
• Flow cytometry was used to identify and quantify polymorphonuclear neutrophils (PMN), lymphocytes, eosinophils, and macrophages.
• Results were compared to a reference method combining LH750 leukocyte counts with manual differential counts from cytospins.

Main Results:

• Flow cytometry assay demonstrated excellent linearity, reproducibility, and a low detection limit, confirming its suitability for ascites cell counting.
• For detecting ≥ 250 PMN/mm³, flow cytometry achieved 100% sensitivity and 100% specificity.
• The automated LH750 showed 100% sensitivity but only 65% specificity for SBP detection.

Conclusions:

• Flow cytometry is analytically well-suited for precise cell counting in ascitic fluid.
• The flow cytometry method is significantly faster and easier to perform than current gold standards.
• Flow cytometry is recommended for rapid and accurate detection of SBP in ascitic fluid due to its high diagnostic performance.