Well Joern, I have seen many, many, many cases of malignant cells treated with anti-CD20 (as well as other antibodies) and they have been CD19 positive. The CD20 is, of course, negative but that is all. I have seen cases of lymphoma in which the treatment does results in selection of cells with a lower level expression of the antigen of interest but that is a different matter. We are talking about a patient receiving Rituxan (anti-CD20) and whether or not all the B cells should be negative for CD19 and CD22. As a rule they aren't . I have been flowing cases of B cell neoplasms that have been treated with Anti-CD19, anti-CD20, anti-CD22 and Anti-CD25 for about 10 years and I have not seen the absence of all the B cell antigens. So, based upon practical experience, I would say you are wrong in this issue. Maryalice Stetler-Stevenson, M.D., Ph.D. Chief, Flow Cytometry Unit Laboratory of Pathology, NCI, NIH Sometimes you're the windshield, sometimes you're the bug. > ---------- > From: Joern Schmitz > Sent: Tuesday, June 4, 2002 2:26 PM > To: Stetler-Stevenso, Maryalice (NCI) > Cc: avispeters@netscape.net > Subject: RE: B cell antibodies > > Unfortunately, Maryalice you are wrong on this issue. B cells tend to shed > or internalize other molecules once you start to bring antibodies onto the > cell surface. From an outside few the B cells appear to be "naked" - CD19 > negative, CD20 negative, ... . This behavior saves some of the malignant B > cells and they start to reexpress their molecules once the antibody > treatment is over and the titers are down. The only way to reliably test > whether you have eliminated the B cells truly is to use an > intracytoplasmatic staining reagent like CD79a. > > Joern E. Schmitz, MD > Assistant Professor of Medicine > Harvard Medical School > > Division of Viral Pathogenesis > Department of Medicine > Beth Israel Deaconess Medical Center > Research East 213D > 330 Brookline Avenue > Boston, MA 02215 > > Phone: 617-667-5206 > Fax: 617-667-8210 > http://research.bidmc.harvard.edu/v_path > > > -----Original Message----- > From: Stetler-Stevenso, Maryalice (NCI) [mailto:stetler@mail.nih.gov] > Sent: Tuesday, June 04, 2002 9:09 AM > To: Cytometry Mailing List > Subject: RE: B cell antibodies > > > Rituxan should not have done that. We have seen CD20 negativity after > treatment but the other B cell antibodies worked well. This unmarked > population could be something other than lymphoid or the CD19 and CD22 > didn't make it into the tube (happens in the best of labs on occasion). > > Maryalice Stetler-Stevenson, M.D., Ph.D. > Chief, Flow Cytometry Unit > Laboratory of Pathology, NCI, NIH > > Sometimes you're the windshield, sometimes you're the bug. > > > ---------- > > From: avispeters@netscape.net > > Sent: Monday, June 3, 2002 4:24 PM > > To: Cytometry Mailing List > > Subject: Re: B cell antibodies > > > > > > Speaking of Rituxan monitoring, we had a Dr. last week that ordered a > > CD20 for Rituxan > > therapy monitoring and he wanted to know how many B cells were > > present. Looking at the > > total lymph gate, there were about 70% T cells (CD3+), about 8% NK > > cells (CD56+16+/CD3-) > > which would leave about 22% that should have been B cells. I could not > > get those B > > cells to stain with CD19, CD20, or CD22. There was always a population > > totally negative > > (0% for all 3 B markers) which amounted to about 20%. I thought the > > Rituxan was only > > supposed to block CD20. Could someone shed some light on this problem > > for me. > > Avis Peters > > United Hospital > > Flow Cytometry Lab > > St. Paul, MN > > > > > > > > "Timothy Singleton, M.D." <tsingleton@smtpgw.beaumont.edu> wrote: > > > > > > > >Cytoplasmic CD79a. > > > > > >Tim Singleton, MD > > >Flow Cytometry > > >Beaumont Hospital > > >Royal Oak, MI > > > > > >>>> Paula Fukushima <pif@mail.nih.gov> 05/24/02 09:40AM >>> > > > > > >Hi List, > > > Does anyone have an idea of B cell antibodies to use to follow > > >disease > > >in B cell lymphomas > > >with patients now being given anti-CD22(Epratuzumab) and > > >anti-CD20(Rituxamab) besides CD19? > > > > > > Thanks, Paula > > > > > > > > >Paula Imus > > >Flow Cytometry > > >LP, NCI, NIH > > >10 Center Drive MSC-1500 > > >Bethesda, Md. 20892-1500 > > > > > > > > > > > > > > > > > > __________________________________________________________________ > > Your favorite stores, helpful shopping tools and great gift ideas. > > Experience the > > convenience of buying online with Shop@Netscape! > > http://shopnow.netscape.com/ > > > > Get your own FREE, personal Netscape Mail account today at > > http://webmail.netscape.com/ > > > > > >
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