Dear Alex,

We ran into the same problem early on; the placenta control was intensely
positive but known germinomas were dead negative.  We no longer use placenta
as a control but rather known positive tumors.  The dilution used for
placenta was not nearly strong enough to stain known positive tumors so now
we optimize our PLAP protocol using germinomas.  I'm certain this will solve
your problem.

Linda

P.S.  Just looked up our optimization notes: we used Dako's polyclonal at
1:3200 for placenta but reoptimized down to 1:100 for germinomas/seminomas!

Linda Sebree, HT
University of Wisconsin Hospital & Clinics
Department of Laboratory Medicine
IHC/ISH Laboratory
A4/204-2472
600 Highland Ave.
Madison, WI  53792-2472

Phone:  (608)265-6596
FAX:  (608)263-1568

> -----Original Message-----
> From:	Alex Brown [SMTP:AlexB@nayrshire.scot.nhs.uk]
> Sent:	Monday, November 30, 1998 11:06 AM
> To:	'Histonet'
> Subject:	Plap
>
> 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.