Jeff

Most mast cells, even non-dendritic ones, stain for CD68 with this
clone(KP-1), that is why we no longer use KP-1. CD68, clone PG-M1, does
not stain mast cells and we prefer it. Tol. blue, will stain up to 90%
of connective tissue mast cells, providing that the fixation in
formaldehyde is short(<24hrs). Longer fixation times will require the
Long Tol. Blue technique or IHC for mast cell tryptase(AA1).
Incidentally mast cell tryptase does not stain histioctes and, since it
requires trypsin pretreatment, as does CD68(PG-M1), it makes your
project a great candidate for double staining( we have been playing with
Dako EnVision double stain Kit with spectacular results!).

Regards

Bryan 

>----------
>From: 	Jeff Silverman[SMTP:peptolab@hamptons.com]
>Sent: 	May 28, 1999 4:52 PM
>To: 	Hewlett Bryan  (CMH); 'histonet@pathology.swmed.edu'; 'Hedley David
>Glencross'
>Subject: 	Re: mast cells, controls
>
>With regard to mast cells, I'm always looking at mesenchymal and
>histiocytic tumors of human skin and in my experience dendritic connective
>tissue mast cells also stain for CD68 (KP-1) a lysosomal glycoprotein. In
>fact, I'm having to do toluidine blue (which gets most of the stromal mast
>cells,no?) to distinguish these from the histiocytes (some CD68+) and
>dermal dendritic cells (CD68 negative)  in a series of histiocytomas. 
>Haven't noticed many mucosal (epithelial?) mast cells in skin though. 
>
>