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Updated: Jun 6, 2026
An Automated Differential Nuclear Staining Assay for Accurate Determination of Mitocan Cytotoxicity
Published on: May 12, 2020
Evaluation of peroxidase activity by alpha-naphthol/pyronine staining compared with benzidine staining in 101 acute
Véronique Latger-Cannard1, Valérie Bardet, Michèle Malet
1University Teaching Hospital, Nancy, France. v.cannard@chu-nancy.fr
Abstract:
Cytochemical detection of myeloperoxidase (MPO) activity, a strong marker for myeloid differentiation, is usually performed by benzidine dihydrochloride staining, with the threshold at 3%. Several reports have demonstrated the potential toxicity of benzidine, and bans have been issued, under French law, prohibiting female technicians from being exposed to the aromatic hydrocarbon group, including benzidine. The aim of this study was to test an alpha-naphthol and pyronine-based substitute using a standardized kit (MYELOPEROXIDASE KIT, RAL [Réactifs RAL, Martillac, France]) to measure MPO activity in blast cells. This prospective, multicenter study made it possible to analyze 101 acute leukemia (AL) cases; it has also demonstrated both the 96% specificity and the 99% sensitivity of the method, with a threshold for positive staining of 3%, as well as good correlation (r = 0.95) between the staining method tested and the benzidine staining method. When using the alpha-naphthol/pyronine-based staining for MPO, the mean number of positive blast cells is statistically lower than that obtained using benzidine, but without incidence on AL classification. These results allow us to conclude that this method makes it possible to classify acute blood diseases by measuring MPO activity using reagents permitted by law, according to a standardized and reproducible protocol.
Insights
A new alpha-naphthol and pyronine stain offers a safe alternative for detecting myeloperoxidase (MPO) activity in acute leukemia (AL) diagnosis. This method is highly sensitive and specific, ensuring accurate classification of blood diseases.
Area of Science:
- Hematology
- Clinical Pathology
- Cytochemistry
Background:
- Myeloperoxidase (MPO) activity is a key marker for myeloid differentiation in acute leukemia (AL).
- Traditional benzidine dihydrochloride staining for MPO poses toxicity risks and is banned in some regions.
- There is a need for safer, reliable methods to detect MPO activity in clinical diagnostics.
Purpose of the Study:
- To evaluate a novel alpha-naphthol and pyronine-based staining kit as a safer substitute for benzidine dihydrochloride in MPO activity detection.
- To assess the sensitivity, specificity, and correlation of the new method with the traditional benzidine stain.
- To determine the clinical utility of the alpha-naphthol/pyronine method for classifying acute blood diseases.
Main Methods:
- A prospective, multicenter study involving 101 acute leukemia cases.
- Standardized cytochemical staining using an alpha-naphthol and pyronine-based kit (MYELOPEROXIDASE KIT, RAL).
- Comparison of results with conventional benzidine dihydrochloride staining, analyzing MPO activity in blast cells.
Main Results:
- The alpha-naphthol/pyronine method demonstrated high sensitivity (99%) and specificity (96%) for MPO detection.
- A strong correlation (r = 0.95) was observed between the novel method and benzidine staining.
- While the mean number of positive blast cells was lower with the new stain, it did not impact AL classification.
Conclusions:
- The alpha-naphthol and pyronine-based staining is a safe, sensitive, and specific alternative to benzidine for MPO activity measurement.
- This standardized and reproducible method allows for accurate classification of acute blood diseases.
- The use of legally permitted reagents ensures compliance and safety in diagnostic laboratories.
