Katie:

Human myeloperoxidase (MPO) is an enzyme found in
neutrophils/polymorphonuclear leucocytes (PMNs). MPO is a major
component of the neutrophil host defense system, catalyzing the production
of the microbiocidal oxidant, hypochlorous acid
(HOCl), from chloride ions and hydrogen peroxide.

Anti-MPO is a specific IPEX marker for neutrophils, and only labels the
granules of neutrophil granulocytes and to a lesser extent, the granules of
monocytes. It is released extracellularly (degranulation) after neutrophil
activation in vitro or in vivo. Extracellular MPO may be an index of
neutrophil activation in a variety of clinical conditions.

Another technique is the enzyme histochemical method: Leder's Napthol AS-D
chloroacetate esterase (CAE). The enzyme remains detectable after routine
formalin fixation and paraffin embedding. The stain is (+) for mast cells
and granulocytes, staining bright pink. It is (-) for other lymphoid cells.
Mayer's hematoxylin is used as a counterstain and may suffice for your
quantitation counts. It is more specific than anti-MPO but not as sensitive.
It really would be awesome to combine CAE or anti-MPO with a Giemsa
technique, but the methanol would destroy the enzyme.

A methyl green pyronin (MGP) may also be of interest to you. The MGP stains
RNA red and DNA green to blue-green. The nucleoli will be red and the
cytoplasm with many ribosomes as is found in plasma cells and transformed
lymphocytes(especially of B cell type) and certain other cells will be
bright red. Nuclei in general appear purple (or blue-green). The rest of the
backround is pale pink to colorless.


Eric Kellar
Histology/Immunohistochemistry
University of Pittsburgh Medical Center



	----------
	From:  Katie Bennett [SMTP:bresee@pilot.msu.edu]
	Sent:  Wednesday, December 30, 1998 11:58 AM
	To:  HistoNet Server
	Subject:  Re: Myeloperoxidase Staining

	To: Clif Chapman, Cathy Fragiskatos, and any other interested
parties.

	What kind of antibody do you use against myeloperoxidase?  Does it
stain
	neutrophils?

	I am trying the myeloperoxidase assay from the AFIP manual with
little
	success.  Here's what I'm trying to do:

	I am trying to do a stain that will allow easy detection for
	quantitation of all the neutrophils in formalin-fixed,
paraffin-embedded
	tissues so I can tell them apart from eosinophils and not rely
solely on
	the morphology of the nucleus.  We have found that a May-Grunwald
stain
	is great for the eos.  We probably could count the neutrophils in
these
	May-Grunwald stained sections, but I would like to find something
that
	makes those neutrophils really stand out.  I am not planning on
doing
	both stains on one slide, but on serial sections.  However, a good
IHC
	stain for neutrophils with a May-Grunwald counterstain would be
awesome!

	Thanks in advance for any info you might have!


	Catherine "Katie" Bresee Bennett
	218G Food Safety Toxicology Building
	Department of Pathology
	Michigan State University
	East Lansing, MI 48824

	ph:  (517) 432-4940
	fx:   (517) 353-9902

	bresee@pilot.msu.edu