Try putting some more rat serum in your blocking step.  I block for 20 min.
with a 10% solution of serum from the host of the secondary which has added
to it about 1% rat serum and I use this for 20 min. before the primary
antibody and then again for 5 min. before the secondary.
Patsy Ruegg

		-----Original Message-----
		From:	james.zimmerman@pharma.Novartis.com
[mailto:james.zimmerman@pharma.Novartis.com]
		Sent:	Tuesday, March 13, 2001 4:44 PM
		To:	Histonet@pathology.swmed.edu
		Subject:	CD3

		Hello,

		 I'm using a CD3 marker grown in mice that cross reacts with
rat.  However
		I'm getting a lot of background staining in

		 axillary tissue on the slides.(mainly heart.) Doe anyone
have any
		suggestions to eliminate this backround staining.  I'm using

		a Vector Elite Peroxidase kit and my CD3 marker is made by
PharMingen. I'm
		staining rat tissue. and I have already tried Casein(Sigma),

		Power Block(BioGenex), an anti-mouse IgG rat adsorbed
biotinylated antibody
		as the secondary antibody.   All help is much appreciated.



		                                   Jim Zimmerman
		                       james.zimmerman@pharma.novartis.com