Re: new antibody

From:Phyllis Davie

Re: new antibody Glen,
    Here is what we use for WT1.  Note that the WT-1 antibody we use has C-19 in parentheses after it.  That is how it appears in the catalog, and is probably the C19 that your pathologist is referring to.  I don’t know anything about a “6F-82”.  We have been using this WT-1 antibody for years, and have extensive experience with it.  I have attached at the bottom of my reply an excerpt from one of our newsletters regarding WT-1, including references.  I hope you find it useful.

WT-1 (C-19) ;  polyclonal rabbit IgG

Best of luck.  

Phyllis Davie
PhenoPath Laboratories--Seattle, WA

        Wilm’s tumor (WT) is an embryonal malignancy of the kidney that affects 1 in 10,000 infants and is observed in both sporadic and inherited forms.   This antibody reacts with the 52 kD Wilm’s tumor nuclear protein of mouse, rat and human origin by Western blotting, immunoprecipitation and immunohistochemistry (inlcluding paraffin-embedded sections).
         Wilms tumor gene product (WT-1) is an antibody with important “contextual specificity” ;  that is, it can be very useful when applied in a restricted differential diagnostic context.  WT-1 is a DNA-binding protein, located in the cell nucleus, that plays a critical role in the development of the genitourinary tract.  The Wilms tumor gene is thought to represent a tumor suppressor gene; unlike more familiar tumor suppressor genes like p53, however, it appears to be operative only in selected cell types.  
   In adult tissues it is expressed in a very restricted subset of cells:  the mesangial cells of the kidney, Sertoli cells of the testis, ovarian stromal cells and ovarian surface epithelium, mesothelial cells in the abdomen and thorax, granulocytes, and some smooth muscle and other stromal cells in the GYN  tract (e.g., myometrium and endometrial stromal cells).
     In the context of neoplasms, its name notwithstanding, WT-1 expression is by no means restricted to Wilms tumors.  In fact, it is rapidly playing an important role in the confirmation of the diagnosis of several different rumors, for which heretofore there have not been good markers.:
1.  Mesothelioma:       WT1, in the context of tumors in the lung, has been demonstrated to be specific for mesothelium and mesothelioma (positive on 13/19 mesotheliomas), discriminating between the latter and primary lung adenocarcinomas, all of which were negative (negative on 45/45 lung adenocarcinomas).   WT-1 has also been reported negative in carcinomas of the breast (0/75) or colon (0/45), although expression has been reported in ovarian serous, but not mucinous, carcinomas(2, 3, 4, 10).  
2.  Carcinomas of Ovarian Surface Epithelial Origin:         WT-1 protein expression has NOT been found in carcinomas of the lung, breast, or colon, but HAS been found in carcinomas of the ovary(4), particularly the serous papillary variant(2).  The results of extensive studies performed in our laboratory in conjunction with Dr. Louise Quenneville, then at the University of British Columbia, document the high level of sensitivity and specificity of WT-1 expression for carcinomas of the ovarian surface epithelium (OSE), particularly papillary serous variants. (52/57 [93%] of serous Carcinomas of OSE were WT1 positive;  while 0/31 mucinous ovarian carcinomas; 0/15 clear cell ovarian carcinomas;  and 0/13 endometrioid ovarian carcinomas were positive for WT1.)
3.   Desmoplastic small, round cell tumor (DSRCT):         Wilm’s tumor rarely enters in the differential diagnosis of ‘small blue round cell tomors’ of childhood that present outside of the kidney.  However, among this latter group, WT-1 expression is highly specific for DSRCT, and it has been recently demonstrated that antibodies to WT-1 can identify this gene product, expression of which is upregulated in DSRCT as a consequence of the t(11:22)(p13;q12) translocation that is specific for this tumor(8, 9).  
4.  Leukemia:         There is considerable evidence that, in the context of hematolymphoid cells and tumors, WT1 expression is specific for a subset of acute lymphoblastic and acute myelogenous leukemias and the blast transformation of chronic meylogenous leukemia(6, 7).  

1.  Antibody spec sheet.  Santa Cruz Biotechnology, 1998.                             
2.  Shimizu M, et al.  Internnational Journal of Gyn. Pathology.  2000 Apr;19(2):158-63.
3.  Amin KM et al, Am J Pathol  146:344-56, 1995                                          
 4.   Kumar-Singh S. et al.,  J Pathol 181:67-74.
5.  Manaloor EJ, et al., Am J Clin Pathol 113:814-22, 2000.                            
6.  Miwa H et al., Leukemia 1992;6(5):405-9.
7.  Menssen HD et al., International Journal of Cancer 1997;70(5):518-23.            
8.  Barnoud R, et al. Pathology, Research And Practice 1998;194(10):693-700.
9.  Charles AK, et al. Histopathology 1997;30(4):312-4.                                          
10.  Gown AM, et al., manuscript in preparation.

on 6/13/02 11:39 AM, Dawson, Glen at wrote:

> All,
> One of my Pathologists is curious about an antibody that goes by a number of
> names: WT 1, C19, or 6F-82.  It may be used to distinguish Adenocarcinoma
> from Mesothelioma.  
> I would appreciate any feedback on any of these three antibodies.
> Thank-you in Advance,
> Glen A. Dawson  BS, HT & IHC (ASCP)
> Lead IHC Technologist
> Milwaukee, WI

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