Dear Rick, In pigs, we have identified two distinct CD21+ cell populations, but each population requires a different technique for its identification: We see a CD21-bright dense network of follicular dendritic cells in follicles by immunohistology. Immunohistology is not however sensitive enough for the clear identification of ordinary B cells. Conversely, the DCs are difficult to isolate (fragile, adherent?) and don't usually appear as isolated CD21-high cells in flow cytometry. However, we can easily obtain and see CD21-dim B cells from pig blood and other tissues by FC. Could your cells be DCs, which for some reason are easier to isolate from spleen? The FS/SS characteristics would fit in with this interpretation. Karin On Wed, 19 Sep 2001 19:26:35 -0400 "Richard K. Meister" <meister.1@osu.edu> wrote: > Hello, everyone: > > I've just finished running a series of flow cytometer samples of various > tissues obtained from necropsies of cats. This was the termination of an > experiment (a cat model of disease). The samples were stained for CD21 > (among other markers). I have used the same anti-cat CD21 monoclonal to > stain blood samples for years and have seen only one CD21(+) population - > and that one is relatively dim (4-decade log scale: negative cells in first > decade; CD21(+) cells in second decade). > > The tissues analyzed this time included blood, spleen, lymph node and > thymus. The CD21(+) populations in most of the tissues looked about the > same as what I have been used to seeing in blood samples. In the spleen, > however, approximately 1/3 of the CD21(+) cells were found in a second > separate "bright" (third decade of the log scale) population. > Interestingly, the spleen cells also demonstrated a different FS vs. SS > profile than normal blood lymphocytes. There is a semi-distinct population > of cells with slightly more FS and SS than normal lymphocytes > (approximately where one would expect to find monocytes). And, the > "monocyte-like scatter" cells are the "bright" CD21(+) cells; and the > "normal-lymphocyte scatter" cells are the "dim" CD21(+) cells. > > I'm trying to interpret these results. I'm hypothesizing that the bright > CD21(+) cells are activated B cells. Do any of you have experience > analyzing CD21 in spleen cells? Is CD21 up-regulated in activated B cells? > > Thanks in advance for your input. > > Rick Meister > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * > * Richard K. Meister Email: meister.1@osu.edu * > * The Ohio State University Voice: (614) 292-9716 * > * Dept. of Veterinary Biosciences FAX: (614) 292-6473 * > * Cytometry Instrumentation Lab * > * 1925 Coffey Road * > * Columbus, OH 43210 U.S.A. * > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * > ---------------------- Dr.K Haverson, Department of Clinical Veterinary Science, Division of Molecular and Cellular Biology, University of Bristol, Langford, BS40 5DU, UK e-mail: Karin.Haverson@bristol.ac.uk Tel.: (44) 117 928 9289 FAX: (44) 117 928 9505
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