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. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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