Re: Alcian blue stains for Barrett's disease

From:"J. A. Kiernan"

You are trying to detect either gastric-type or
intestinal-type epithelium with cells secreting mucus, 
which are not present in normal oesophageal epithelium. 

Alcian blue atpH 2.5 will detect both sialomucins and 
sulphomucins, so this is the pH to use. PAS detects 
some sialomucins and also "neutral mucins" that are
not stainable by alcian blue. 

Traditionally the alcian blue staining is done before
the PAS. If alcian blue is done second, the PAS-positive
substances are a more purplish shade of colour because
the blue cationic dye is attracted to the red anionic 
tissue-Schiff complex. (This may result in more intense
staining of weakly PAS-positive materials.) For 
diagnosing Barrett's oesophagus you are not doing 
a critical histochemical study of the different types 
of mucus; you need a sensitive stain that picks up
all types and helps to demonstrate the secreting
cells. Together, alcian blue pH 2.5 and PAS will detect
all the mucus that's there, whatever the sequence of
application. 

If you use an alternative to alcian blue 8G, such as 
alcec blue (? no longer sold) or the "alcian blue
pyridine variant" sold by Sigma/Aldridge, there
may be some extraction of bound dye by the acidic
reagents used in the PAS method. It would seem wise
therefore to apply these dyes after rather than 
before PAS, and accept the somemwhat different
colour scheme. True alcian blue 8G (CI 74240, Ingrain
blue 1) is converted during staining and washing to 
copper phthalocyanine (CI 74160, Pigment blue 15), 
which is completely insoluble and cannot be removed 
by any later treatments applied to the sections.

There are plenty of published papers about alcian
blue and related dyes and how to use them. Some
are cited in the new 10th edn of "Conn's Biological
Stains" (pp 385-388). There are important papers
establishing the validity of alcian blue pyridine 
variant by Churukian et al (2000) Biotech. Histochem.
75:147-150, and by Henwood (2002) Biotech. Histochem.
77:93-94. 
-- 
-------------------------
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
   kiernan@uwo.ca
   http://publish.uwo.ca/~jkiernan/
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"Jennings-Siena, Debbie" wrote:
> I was wondering if anyone could suggest the appropriate Alcian Blue (and pH) stain for Barrett's disease of the esophagus.  I have to admit that trying to decipher all of the mucins boggles my mind.  There is a discussion going on here at Baylor as to whether Alcian Blue pH 2.5 or pH 1.0 is better and is it better with or without PAS counterstain.  I know that some of you Histology Guru's will have the answer readily available.  Thanks in advance for any and all help.
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