We also have had this problem in various tissues including skin and
autonomic ganglia. In our hands the blocking kit from Vector Labs made
little difference. Streptavidin IS a bit better than avidin in most
tissues.  I also would like to know either what the endogenous ligands may
be (I doubt it is all biotin) or how you can get rid of the binding...It is
sufficiently bad in our ganglia that we cannot use biotinylated secodary
antibodies to localise synaptic boutons, especially if Cy3 is used as the
fluorophore...
Ian Gibbins
Department of Anatomy and Histology
Flinders University of South Australia
Phone:  +61-8-2045271
FAX:    +61-8-2770085
 
I'm afraid I did not get your point entirely, but
Anyhow one should also take into consideration
that there is possibilities that the tissue contains
receptors for Fc portion of  immunoglobulins. In that case it is
beneficial to use Fab-fragments of the antibodies.
Riitta Miettinen, Ph.D.
Dept. of Neurology
Univ. of Kuopio
P.O. Box 1627
FIN-70211
FINLAND
E-mail: [log in to unmask]
Tel: 358-71-162761
Fax: 358-71-162048