As a general rule 10x10⁶ cells per ml is a good starting point, but the best concentration at which to suspend your cells is dependent on the nature of the sample.

Samples that require little or no dissociation (e.g. peripheral blood, bone marrow, lymph node, non-adherent cell lines) can be suspended as high as 20x10⁶ cells per ml.

Samples prepared by dissociation, especially those likely to be "sticky" (e.g. brain, liver, kidney, adherent cell lines), should be more dilute to minimise clumping and thus reduce the chance of causing blockages in the flow cytometer. Such samples could be suspended at 3-10x10⁶ cells per ml.

If in doubt, suspend samples in a higher concentration - we can easily dilute the sample to a lower concentration. However, please keep in mind the following minimum required volumes for running samples:

• When using the high-throughout plate sampler on the LSRIIs, this will be the "dead" volume for the plate type you are using (typically 50ul, but ask a FlowCore staff member if in doubt).
   
• For all other applications: 200ul.