Quick staining technique for myeloperoxidase using potassium iodide and oxidized pyronine B

Area of Science:

• Hematology
• Clinical Pathology
• Cytochemistry

Background:

• Myeloperoxidase (MPO) staining is crucial for diagnosing and classifying leukemia.
• Conventional MPO staining methods, like the Washburn benzidine method, have limitations.
• The need for a more stable and efficient MPO staining technique is evident.

Purpose of the Study:

• To introduce and evaluate a novel Myeloperoxidase (MPO) staining method using oxidized Pyronine B (PyB).
• To assess the clinical application and diagnostic accuracy of the new PyB-based MPO staining technique.
• To compare the efficacy of the novel PyB method with the conventional benzidine staining for MPO.

Main Methods:

• Preparation of a stable oxidized Pyronine B (PyB) solution as a chromogenic reagent.
• Formulation of the MPO working solution with phosphate buffer, potassium iodide (KI), and oxidized PyB.
• Staining of bone marrow smears from 229 patients (acute leukemia or normal) using both the new PyB method and the conventional benzidine method.

Main Results:

• The oxidized Pyronine B method produced vibrant red cytoplasmic particles and bluish-green nuclei.
• No significant difference in positive detection rates was observed between the PyB method and benzidine staining.
• The new method demonstrated reagent stability and eliminated variability from hydrogen peroxide (H₂O₂) concentrations.

Conclusions:

• The novel Pyronine B staining method is a reliable and effective technique for MPO detection in leukemia diagnosis.
• This method offers advantages of simplicity, time-saving procedure, and enhanced reagent stability.
• The PyB-based MPO staining technique presents a superior alternative to conventional benzidine-based methods.