Myeloperoxidases Stains

Myeloperoxidases Stains

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  Rabab Salama Clinicaland Chemical Pathology Consultant, HCQM Specialist 1
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  Study of chemicalelements in cells. 2
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  Substrate + Enzyme>>>> Product + Visible product <<<< Chromogen 4
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  Types Myeloperoxidase (MPO) Leukocyte AlkalinePhosphates (LAP or NAP) Acid Phosphates, TRAP Estrase Sudan Black B stain (SBB) Iron stain Reticulin stain Periodic Acid Schiff (PAS) 5
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  PEROXIDASE STAIN Purpose:  Todifferentiate a myelogenous or monocytic leukemia from acute lymphocytic leukemia.  Peroxidase is present in the primary azurophilic granules of neutrophil, eosinophil and monocyte & activity increased with maturation, no activity is found in red cells or lymphocytes. 6
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  PEROXIDASE STAIN Principle:  Inthe presence of myeloperoxidase, H2O2 oxidizes substrate ( benzedine or DAB) forming black ppt. 8
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  Reagents  Fixatives Formal ethanol(formaldehyde and absolute ethanol)  Substrate Benzedin (carcinogenic) –diaminobenzedine (DAB) H2O2  Counterstain Mayer’s hematoxylin PEROXIDASE STAIN 9
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  PEROXIDASE STAIN : Red – brown peroxidase found in: neutrophil and eosinophil {promyelocyte – Myelocyte – Metamyelocyte}  Finely granular staining found in: - Monocyte  Negative stain found in: ( early Myeloblast, lymphblast, basophiles and plasma cell) 10
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  NOTES:  MPO issensitive to light, smears should be stained immediately and stored in dark.  Positive control from healthy individuals.  Overincubation: false positive peroxides in RBCs. 11
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  Myeloperoxidase (MPO) bluish-black granulesred brown precipitate 12
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  Myeloperoxidase stain, bonemarrow aspirate The red granular staining peroxidase activity. 13