You are probably experiencing ionic interactions where DAB is attracted to
Plus Charge coating on glass slide or poly l lysine slides (you did not say
you used these?) 

We had the "ugly ring around the section" with AEC and other chromogens
using Erie Plus charge slides.  Good rinsing technics help.  Ready to use
chromogens gave more problems and we solved this with next commentary. 

Make sure buffers/diluents contains detergent, 0.05% Tween 20 will work.
Another trick is to do final buffer/0.05% Tween 20 rinse BEFORE a ready to
use chromogen (we found this with AEC+, AEC, DAB+ from DAKO. With Vector
chromogens, they give instructions on how to do this, with both Vector Red
and Vector Blue (the Tween also makes these chromogens very crisp, less
diffuse appearance).  Vector has their instruction sheets on their website - 

If you need more info on detergents and how they work, go back in Histonet
Archives - very enlightening. 


Gayle Callis
MT,HT,HTL(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology - Marsh Lab
Montana State University - Bozeman
S. 19th and Lincoln St
Bozeman MT 59717-3610

406 994-6367 (lab with voice mail)
406 994-4303 (FAX)

email: gcallis@montana.edu