Lynette, Its not so much the positive control tissue as the antigen it's detecting; there are antigens that are quite labile and so lose their reactivity over time when the positive control tissue slides are stored at room temperature. Off the top of my head, ER, PR, Ki67, bcl-2, bcl-6 are some that come to mind...there are a number of others. So we store some previously cut control slides at RT and others at -20 degrees C depending upon the antigen they will be used for. You can find further information regarding the more sensitive antigens in the Histonet Archives.
Hope this helps, Linda A. Sebree University of Wisconsin Hospital & Clinics IHC/ISH Laboratory DB1-223 VAH 600 Highland Ave. Madison, WI 53792 (608)265-6596 -----Original Message----- From: histonet-boun...@lists.utsouthwestern.edu [mailto:histonet-boun...@lists.utsouthwestern.edu] On Behalf Of Lynette Pavelich Sent: Tuesday, May 26, 2009 1:16 PM To: histonet@lists.utsouthwestern.edu; f...@ufl.edu Subject: [Histonet] IHC control debate Hello, I need help from all of our IHC expert guru's! We have a debate going on about the known positive control blocks. All are FFPE with 8-48 hrs in formalin. All have been tested and have been approved for use as positive controls. We currently cut the positive control from the block as needed. I have learned that some controls do start to deteriorate over time, tonsils for example. But, is there a list, an article, SOMETHING that can guide me so that we can cut some of these controls ahead of time? This would not only save tech time, but would further the use of our controls. In cutting the block, some of the good control is wasted and some positives are hard to find. My argument is that the purchased controls work wonderfully, even after a very long time and our improved detection kits have improved so much over the years, it makes this possible. If there is no published article out there, I implore you experts to please help us in this area. Would also like to hear from the technical experts from our suppliers too! Until then, the debate continues on!!!!!!! Thank you!! Lynette _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet