[Histonet] IHC neg. controls (Friday rant)

shive003 <@t> umn.edu shive003 <@t> umn.edu
Sun Jun 8 21:06:31 CDT 2008

I agree with Rene'... for instance, if you're running three different 
cytokeratins on your case tissue, all mouse monoclonals, all requiring 
enzyme digestion for unmasking antigens, all with the same detection system 
and protocols... why run 3 separate negative controls on the same block? 
They'll be identical copies of each other. All you're doing is wasting 
reagents, supplies, and precious tissue.

One negative control per block per pretreatment and/or detection system. 
More than that is just illogical to me.

Jan Shivers

On Jun 6 2008, Rene J Buesa wrote:

> If you detection system is the same and all the procedure is the same for 
> the 6 Abs, except for the Abs, you will need only ONE negative control 
> per tissue, per block, but not per Ab.
>  René J.
>Patti Loykasek <ploykasek <@t> phenopath.com> wrote:
>  Can someone rationalize to me the practice of running a negative 
> control for every antibody in an IHC workup? For example, six antibodies 
> & six negative controls??? This makes me crazy. Just had a case, needle 
> biopsy, where this occurred at an outside institution, and now we don¹t 
> have enough tumor left to run more IHC & get a diagnosis. It borders on 
> malpractice IMO.
> On the AP CAP checklist ANP.2270 Are appropriate negative controls used? 
> The comment has the following (near the end):
>A negative tissue control must be processed for each antibody in a given
>run. Any of the following can serve as a negative tissue control:
>1. Multitissue blocks. These can provide simultaneous positive
>and negative tissue controls, and are considered ³best practice²
>2. The positive control slide or patient test slides, if these
>slides contain tissue elements that should not react with the antibody.
>3. A separate negative tissue control slide.
>I think it best to asses this negative tissue control on your positive
>controls that should contain negative elements. Plus, use known negative
>elements on the patient slides. The patient tissue is precious & these
>patients have undergone procedures that have associated morbidity. I can¹t
>see using up patient tissue for multiple negative controls & Having the
>patient have to undergo another procedure!
>Ok &shy; I¹ll stop now.
>Patti Loykasek
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