Hi Karim, We have been using flow to assess numbers of cells in migration assays by adding beads to the sample. Basically we are adding a known amount of unlabelled Calibrite beads (and we know the number per ul by counting) to a known volume of cells and running through the cytometer. We then calculate a value for cells per ul from: [number of cells in area of interest/number of beads collected] x [bead count per tube/ sample vol in ul] There are a number of caveats in that your bead counting has to be accurate, your pipetting needs to be accurate, there needs to be as constant a flow rate as you can get and the beads and cells need to be un-clumped. However we have found that this is a good quick method of seeing certainly relative differences in cell numbers between samples. I am sure those involved in absolute cell counting will have alternative approaches! Good luck! Derek On Thu, 14 Jun 2001, Karim Vermaelen wrote: > Hi everybody , > Can anyone recommend a microsphere kit for performing simple cell counts > on numerous samples using the FACS? BD's Truecount beads are only sold > along with a MAb. Our cells do not have to be labelled. Any simpe > alternative? (NB: our good ol' Coulter particle counter is dead) ************************************************************************ Derek Davies Voice: (44) 020 7269 3394 FACS Laboratory, FAX: (44) 020 7269 3100 Imperial Cancer Research Fund, e_mail: derek.davies@icrf.icnet.uk London, UK mobile: 07790 604112 Web Page: http://www.icnet.uk/axp/facs/davies/index.html In tenebris lux *************************************************************************
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