Michelle, 

I am not sure how long controls last, I have not done a scientific study as
I am sure some have. Through experience we have found that paraffin blocks,
even unsealed, seem to retain antigenicity for a very, very long time.
Years. As for cut control slides - for some antigens (HER2) cut sections can
remain at room temperature for just a matter of days before the antigenicity
starts to decline. Immuno control slides deteriorate faster if they have
been incubated or stored at room temperature. From my experience, I would
recommend that controls slides be cut, but not incubated, and stored in the
refrigerator under dry conditions. The expiration on these slides is up for
grabs, I would be interested in what others have to say. We go through our
breast marker controls very rapidly and all others have a 1 year expiration
after they are cut. However, we go through the controls in a matter of a few
months.

Good luck,
Marg

Marjorie Hagerty H.T. (ASCP) H.T.L., Q IHC
Supervisor, Anatomic Pathology
Eisenhower Medical Center
39-000 Bob Hope Drive
Rancho Mirage, CA 92270


Marg


-----Original Message-----
From: Michelle Peiffer [mailto:mlk101@psu.edu]
Sent: Thursday, April 05, 2001 7:29 AM
To: histonet@pathology.swmed.edu
Subject: storing controls


Thanks to all who responded about my IHC decreased staining post.

Several people have mentioned storage of the controls.  Some are purchased
slides, so obviously they are precut and they are stored in the
refrigerator.  But most are freshly cut from blocks which are stored at
room temperature.  I was under the impression most people store blocks at
room temperature, is this correct?  How long can controls last?  We just
started doing histology so our oldest blocks are only 6 months old.


Michelle


Michelle Peiffer
*************************************************************
Electron Microscope Facility for the Life Sciences
Penn State University Biotechnology Institute
001 South Frear Lab
University Park PA 16802

phone: 814-865-0212
email:  mlk101@psu.edu
**************************************************************