Bunny Cotleur writes- >I wonder if I could gather some opinions on releveance as it relates to >minimum numbers of events collected. >I am assisting a lab in developing FACS analysis of PBMC's and monocytes >in CSF. They informed me that when they run FACS, they are "lucky" to >get 100 events. I raised the questions of relevance, stating that those >100 "events" could as easily contain some non-cell events as cell >events. They insist their data is good becasue it compares somewhat (?) >with a lab in Europe they are collaborating with. We have had many >conversations on this. >(I should mention- neither lab has direct FACS experience. They got all >their protocols second hand, and just collect what they collect). >Additional information: they are looking at chemokine expression >(another difficult task) on these few cells- and I believe they are >using the PBMC's to set up isotype controls. I doubt they even use comp >controls. > >Please throw your 2cents my way. And if any of you do this type of >analysis (few cells) with alternative techniques- I'd love to hear about it! Attallah et al (Attallah AM, Yeatman TJ, Noguchi PD, Johnson JB: Antibody-dependent cell-mediated cytotoxicity: detection by automated flow cytometry with ultramicro techniques. Science 1980; 209:404-6) found, using microsyringe pumps for sample delivery, that antibody-dependent cell-mediated cytotoxicity could be measured by analyzing as few as 1000 leukocytes. With the volumes and delivery systems used on conventional instruments, I'd worry, as Bunny does, about how real the 100 events her colleagues measure might be. This problem is tailor-made for the CompuCyte LSC, although, if you don't have access to one, it might be possible to hook the appropriate fluidics up to, say, a FACScan and analyze very small numbers of cells. -Howard
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