False negatives using monoclonalPLAP
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From: | Dave Tacha <dtacha@ncal.verio.com> (by way of histonet) |
To: | histonet <histonet@magicnet.net> |
Reply-To: | |
Content-Type: | text/plain; charset="us-ascii" |
In Response to Alex Brown:
There is a great abstract from the IAP meeting comparing monoclonal a
PLAP
to a polyclonal PLAP. The polyclonal marks 80%-90% of classic seminoma
and
the monoclonal only marked 30-40%. The total percentage of all germ
cell
tumors studied was 85% with the polyclonal versus 15% with the
monoclonal.
However both mark 100% for placenta. I would not recommend a monoclonal
PLAP for screening. Dako recently replaced their polyclonal with a
monoclonal. I've talked to other techs and they say it does not perform
as
good a the polyclonal. After seeing results from the IAP paper, I would
like
to see a paper comes out comparing this new antibody. I feel the same
way
about a monoclonal AFP or synaptophysin verses a polyclonal AFP or
synaptophysin, At present, I have never found a monoclonal AFP or
synaptophysin to out perform a good polyclonal. These are broad
screening
antibodies that stain many different kind of tumors, both well and
poorly
differentiated. AFP, synaptopysin, and PLAP polyclonal antibodies stain
a
broader range tumors versus monoclonals. I am not willing to give up
their
performance record for monoclonal antibody that marks 50% less tumors.
I
will be even more blunt. Do not use a monoclonal PLAP until you have
performed side by side tests! You are already seeing false negatives in
your lab.
David Tacha HTL (ASCP)
Biocare Medical Laboratories
Alex Brown wrote:
> Hi All,
> We've recently been having some trouble with our Placental
> Alkaline Phosphatase (Plap). i.e. variable results. Some tumours we
> expected to be positive, have been negative although the control (
> normal placenta) has been strongly positive. In one case recently, a
> tumour in testes (well fixed), allthough the tumour cells were
> unexpectedly negative, there was positive staining in smooth muscle
> fibres.
> We use Dako's Primary (M7191, Clone 8A9) at 1:50 for 30mins ,
> microwave/pressure cook, and use Biogenix's HRP Kit and DAB. Staining
is
> carried out on the Optimax II.
> Anyone else had any similar problems with this ??????
> Regards
> Alex. Brown
> Crosshouse Hospital
> Kilmarnock, Scotland.
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