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

Area of Science:

• Clinical Chemistry
• Hematology
• Flow Cytometry

Background:

• Cell counting in ascitic fluid is challenging and time-consuming with current methods.
• The gold standard involves automated counters or manual chambers with cytospin differential counts, which have limitations.

Purpose of the Study:

• To develop and validate a novel flow cytometry assay for rapid and accurate cell counting in ascitic fluid.
• To compare the performance of the new flow cytometry assay against automated cell counters and manual methods.

Main Methods:

• A flow cytometry assay was developed to identify and quantify polymorphonuclear neutrophils (PMN), lymphocytes, eosinophils, and macrophages in ascitic fluid.
• The assay was validated for linearity, reproducibility, and detection limit.
• Results were compared to a reference method combining automated leukocyte counts (LH750) with manual cytospin differentials.

Main Results:

• Flow cytometry demonstrated excellent linearity, reproducibility, and a low detection limit for ascitic fluid cell counts.
• The flow cytometry assay achieved 100% sensitivity and 100% specificity in detecting spontaneous bacterial peritonitis (SBP) by identifying PMN counts ≥250 cells/mm³.
• The automated cell counter (LH750) showed 100% sensitivity but only 65% specificity for SBP detection.

Conclusions:

• Flow cytometry is a well-suited analytical method for cell counting in ascitic fluid.
• The flow cytometry assay is recommended for rapid cell counting in ascitic fluid due to its ease of use, speed, and high diagnostic accuracy for SBP.
• This method improves upon existing techniques for diagnosing SBP.