[Cytometry] Population that "disappears" at low flow rate?!

Vinko Tosevski vinko.tosevski at gmail.com
Mon Jul 13 04:19:40 EDT 2009


Dear all,

I would like to ask you about the a "phenomenon" that I saw the other
day on our Aria I (colleague saw it on our Canto II as well). I was
working with normal murine spleen. When I had a bit higher flow rate
(10-15000 evt/s), the scatter dot plot looked OK (FSC vs SSC). When
the flow rate would go below 10000 evt/s, the events from lymphocyte
region would start disappearing, eventually vanishing from the dot
plot, leaving just events that had lower FSC and lower/equal/higher
SSC (basically, I couldn't see any obvious change in SSC readout)...
What's that? How to explain that?

The only case where I saw population disappear was when the noise
overwhelmed the machine (to high voltage at too low threshold), but
then I would also see unnaturally high event rate - here, in this
case, the event rate was stable and I saw no obvious wrong readings...
but the population just wanished. When I increased the flow rate, the
population was back again...

Can you, please, explain me the background of this "phenomenon"?

Cheers,
Vinko

---
Vinko Tosevski
Zurich University Hospital
Department of Pathology
Institute of Experimental Immunology
Building 44, Room J42
Winterthurerstrasse 190
CH-8057 Zurich
Tel: +41 44 6353706


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