Louise,
	Where is the background - just generalized throughtout the section
or in specific cells? I would not hesitate to use 3%BSA as a protein block
as well as blocking for endogenous peroxidase. I have also found that
background can be decreased by monitoring the substrate time and
concentration as well. Bottom line is the signal to noise ratio and how
perfect you would like it to be. I like perfection but am unable to attain
it in every stain.
Cynthia Favara
NIAID/RML/LPVD
903 South 4th Street
Hamilton, MT 59840
PH: 406-363-9317
FAX: 406-363-9286