Sorting and viability

Martin Foerster Martin.Foerster at
Thu Jul 26 08:18:52 EST 2001

Hi Flowers,

I'm a novice in cell sorting and trying to sort eosinophils for further culture. The
problem is the viability of the sorted eos which is clearly lower than that of unsorted
cells. We shurely have to replace the FACSFlow we use as sheathfluid by PBS in the
future. But we also tried to reduce the sample pressure. Our sorter is a Cytomation
MoFlo which usually runs at 60.2 psi sample pressure and 60.0 psi sheath pressure. When
reducing the pressure, we were told, the difference between sample and sheath pressure
should be larger than on high pressures to prevent the sample tube from filling with
sheath fluid and to get beads or cells to the nozzle at all. The lowest sample pressure
which we didn't get a reflow with was about 58 psi when we lowered the sheath pressure
down to1 psi. In the mailing I list I found that many people are sorting at about 30
psi, but I don't know if this is sample or sheath pressure.
So, my questions are:
1. What pressure is critical for after-sorting viability: sample or sheath?
2. If it is sample pressure, how do I get to 30 psi?
3. Has anyone sorted eos and further cultivated these cells? Is pressure critical at all?

Thanks in advance

Martin Förster

Inner Medicine IV / Pneumology
Erlanger Allee 101
07740 Jena / Germany
Tel.: +49 (0)3641 939 580
FAX: +49 (0)3641 939 572
e-mail: martin.foerster at

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