Brett,
i have had the same experience with cd31, as a matter of fact we have tried
many antibodies for endothelial cells to show angeogenisis, cd 31, cd 34,
factor 8, vegf, collagen 4, several endoglin antibodies and more.  but our
best results have come from an endoglin antibody from Santa Cruz which is
really TGFbR3.  i can give you the clone from work on monday if you like.
this antibody shows very early endothelial cells, we are very happy with it.
i am planning to present a poster at NSH on our search for the best
endothelial cell marker.
Patsy Ruegg 

-----Original Message-----
From: Connolly, Brett M
To: 'HISTONET'
Sent: 5/18/01 2:10 PM
Subject: CD31 in rat

I have been trying to optimize CD31 in frozen rat brain using
Pharmingen's
clone TLD-3A12 for rat CD-31. The rats have gloisarcoma tumors and I
want to
look at tumor vascularity. I can get great, clean staining in the
non-tumorous areas of the brain, but the tumors are a mess of
nonspecific
staining where all cells are picking up the chromogen and nothing
specific
can be discerned. The method is acetone fixation, ABC with DAB/NiCl.
H2O2
blocking, serum blocking, avidin/biotin blocking, non-serum blockers and
biotin-free detection have all been tried as have zinc/tris and formalin
fixation. Negative controls are clean. I' m in the process of looking at
the
gliosarcoma cell line to see if  the antibody recognizes the tumor cells
in
vitro.  Just wondering if anyone has had a similar experience??

I too like Fawlty Towers, but I also enjoy 'Keeping Up Appearances'.

Brett     

Brett M. Connolly, Ph.D.
Merck Research Laboratories
Dept. of Pharmacology
WP26A-3000
PO Box 4
West Point, PA 19486
Ph. 215-652-2501
fax. 215-652-2075
e-mail. brett_connolly@merck.com