Sorting Dilemma

From: Andrew Oberyszyn (oberyszyn.2@osu.edu)
Date: Wed May 16 2001 - 15:27:59 EST


Hi Everybody in Flow Land,
I have a sorting dilemma which I hope someone can help me with.
The problem I'm having is that I don't see any cells (flourescence or
FS/SS) when checking the purity!
I double checked the delay and phase which were correct.
I thought the cells might be sticking to the tube so I spun them down and
did a cell count.  It was right on with what the cytometer said I had.  I
tried running these in a small volume 200ul but still did not get
anything.  Initially I was trying to reanalyze small numbers (<20,000
sorted cells).  When I sorted 50,000+ cells, I was able to see some (1-10%)
cells upon reanalysis.  I tried doing the same thing using Flow-check bead
with the same results.
I did not see this problem with other sorts I've done where I've sorted
anywhere from ~50,000 to 1.2 x 10^6 human lymphocytes into collection tubes.


Anybody have any idea why I can't see the cells which are clearly there?

INFO:
I am sorting mouse splenocytes which have been separated on a CD4 MACS
column.
The cells are FITC/PE stained.
The sorter I have is a Beckman Coulter Elite (with the ESP module).
cells are freshly isolated and kept in media with 10% FCS
Sort collection tubes contain media with ~10-20%FCS
1 drop sort used; tried various combinations of Coincidence abort and PPU

Any help would greatly be appreciated!!

Thanks in advance!
Andy

(:)-(:)-(:)-(:)-(:)-(:)-(:)-(:)-(:)-(:)-(:)-(:)-(:)-(:)
   Andy Oberyszyn, M.S.
   The Ohio State University
   Analytical Cytometry Laboratory
   416 Comprehensive Cancer Center
   410 West 12th Avenue
   Columbus, Ohio 43210
   Tel: 614/292-FLOW(3569)
   Fax: 614/292-7335
   E-Mail: cytometry@osu.edu

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