[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"?


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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