Re: Expression of Annexin on Activated platelets
Arnold Pizzey (a.pizzey@ucl.ac.uk)
Mon, 15 Jul 1996 15:08:46 +0000
At 10:07 AM 11/8/96 -0500, you wrote:
>
>Greetings from the University of Vermont
>
> An investigator wants to look at increased expression of annexin
>fitc on activated platelets. Is there any way of differentiating an
>increase in the intensity of the signal due to upregulation on such
>platelets from increased signalling due to the beginning of aggregation. It
>appears that the higher level signalling also demonstrates increasing FS and
>SS.
> I would like to know whether measuring total fluorescence, as
>opposed to looking at the mean intensity of the signal is the answer. We
>have an EPICS Elite, if anyone has any insights, they would be greatly
>appreciated.
>
>
> Colette Charland
>
>
>
Greetings Colette.
Aggregated plateletts may be discriminated to some extent by plotting
Forward Scatter intergral against Forward Scatter Peak; aggregates fall away
from the line of linear relation between the two parameters. However I
imagine this may be of little use as you are performing a selection which
may exclude the very particles you wish to analyse.
It may be possible to (as you suggest) to merely base your analysis on the
mean cell fluorescence of the total platelette population, this however
makes some assumptions on the ability of the cytometer to acurately measure
the anexin V signal from aggregates.
If you looking at annexin V binding as a function of an activation event
then it may be inappropriate to inhibit aggregation. If this is the case I
think that I might look into the possibility of analysing these samples on
a fluorimeter
Best wishes.
Arnold.
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