Hi Amos,

I disagree.  The purpose of the negative control is (at least in my mind) a
control on endogenous activity in each tissue and non-specific binding.  For
example if you are using an avidin-biotin method, then the negative control
would indicate any endogenous biotin activity that had not been blocked,
thus preventing confusion by whomever is interpreting the results.  The same
for other tissue components that pick up non-specific staining..... if your
negative has positivity, then it can be "mentally subtracted" or in a severe
case, rerun using different blocks, or techniques,etc.

Bonnie Whitaker
UT--Houston

----- Original Message -----
From: amos brooks <atbrooks@snet.net>
To: Mackinnon, John <jmackinnon@lakeridgehealth.on.ca>
Cc: HistoNet (E-mail) <HistoNet@pathology.swmed.edu>
Sent: Saturday, February 26, 2000 8:45 AM
Subject: Re: Negative Reagent Controls For Immuno


> Hi,
>     I see no use running a negative control for each block if the
processes are
> identical. Exception being the Herceptest, solely because it is FDA
approved,
> and that is what they expect of this method. It is appropriate to have one
> representative control but it needn't be one for each block. That would be
very
> redundant, impractical, and unnecessary. We've never had a deficiency for
this
> and I would like to hear of anyone who has.
> Amos Brooks
>
> "Mackinnon, John" wrote:
>
> > When running negative reagent controls you should be running a negative
for
> > each block, if you are running both monoclonal and polyclonal antibodies
you
> > should run a negative for each of these.  If one of your antibodies
requires
> > HIER another enzyme and one no pretreatment you should be running a
negative
> > for each of these.  All of your controls must be treated the same way
that
> > your test sections are treated, if you don't do this you are not really
> > controlling the procedure.  Expense is no excuse for not running proper
QC.
> > I can't remember ever hearing a biochemist saying that they were not
going
> > to run all of the appropriate QC because it seemed excessive and
expensive.
> >
> > John MacKinnon MLT, ART
> > Senior Technologist, Pathology
> > Lakeridge Health Oshawa
> > Ontario, Canada
>
>
>
>