Hi Timothy,
Sounds like the slides are not being rinsed properly, and that the
pap pen demarkation is creating a "well" where  antibodies/proteins
etc are being trapped. i had this problem when using multiwell slides
for in situ. My problem stopped when I changed to ordinary coated
slides. In your instance i am not sure - perhaps a little surfactant
added to the wash buffer?  Try checking with the stainer's technical
dept. maybe they have the answer.

Louise Taylor
SAIMR
Johannesburg
South Africa





On  6 Oct 98 at 8:08, Coskran, Timothy M wrote:

> Hello,
>
> Does anyone know of a source for I-CAM that will work on paraffin and be
> reactive with rat tissue?
>
> We've been having an annoying problem pop up with the last few immuno runs.
> Our slides have "developed" a brown square that covers the tissue section.
> The square is outlined where the pap pen line would have been before being
> dissolved.  The funny thing is that it happens on all the slides except our
> negative control.  This problem seems to only happen on our immunostainer
> and has been showing up with a number of different antibodies.  It happens
> occasionally on runs done on the bench but few and far between and when it
> does occur it usually is with one to two slides max. Any ideas?
>
> Tim
>
>