RE: [Histonet] Universal (protein) block for IHC

From:Browning Deb

May I ask, what do you use to block, or is this step skipped altogether?
There was a time we couldn't use a blocker because it reacted with the
antibody diluent, so we actually saved time.  Now we have switched to kits
that come with blocker, so we use it, with no adverse effect other than
increased TAT.

-----Original Message-----
From: Richard Cartun []
Sent: Thursday, April 07, 2005 2:08 PM
Subject: Re: [Histonet] Universal (protein) block for IHC

I find it interesting that some labs still use a protein or normal sera
block.  We stopped doing this years ago (for paraffin sections) and we
never see any nonspecific staining.


Richard W. Cartun, Ph.D.
Director, Immunopathology & Histology
Assistant Director, Anatomic Pathology
Hartford Hospital
80 Seymour Street
Hartford, CT  06102
(860) 545-1596
(860) 545-0174 Fax

>>> "Johnson, Teri"  04/06/05 05:34PM >>>
Has anybody converted to using a universal protein block (casein) for
their immunohistochemistry protocols rather than using species
normal sera?  For those who have made the conversion, did you have to
make any changes to your methodology or did you just plug it in to
protocol and run?  Did you notice any difference in the staining
intensity for known antibodies (stronger, weaker, no change)?  Are you
also using it as a secondary antibody diluent or for washes?  Finally,
are you using commercially available reagent or are you making your
Thanks so much!

Teri Johnson
Managing Director Histology Facility
Stowers Institute for Medical Research
1000 E. 50th St.
Kansas City, Missouri  64110 

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