> > Intermittently, we experience what appears to be cell carryover >from one tube to the next when acquiring on our FacsCalibur with the >automated sample loader attachment. These cells >form small populations which appear to express bizarre antigen combinations >until it is recognized that these are cells from the immediately previous >tube, stained with different antibodies. When a re-stain is performed, >using a new aliquot of the specimen, these cells disappear. When the >contaminated tube is later re-run, however, the cells are still there, >indicating that a portion of the cells from the first tube actually entered >the second tube. We initially suspected that the tube-tube contamination >occurred before they were put on the cytometer, but that is apparently not >the case, as in one case data from all tubes looked normal, with no >contamination, but when the case had to be re-run for an unrelated reason, >one tube was now contaminated with cells from the immediately preceeding >tube, and when it was run a third time, the cells were still there. We >thought there might be a problem with the pump mechanism, but it has been >replaced (by a B-D FSE) without correcting the problem. Has anyone else >ever experienced >this problem? Any ideas what might cause it? Thanks, Richard McFarland UT Southwestern at Dallas
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