>
>Dear All,
> Got an unusual problem that we see quite often these days.
>
>When running cytoplasmic markers (TdT, Mu etc) we see the fluorescence
intensity
>of both the FITC stained cells and non specifically stained controls creep up
>the 4 decade log scale, levelling out after 2 minutes and up by 1 decade.
>Re-running the SAME tube shows the same pattern, starting at baseline and
>levelling off 1 decade up.
>No changes in FS, SS or aquisition rate are evident.
>We never see this with surface staining at all and it doesn't happen with all
>our Leuks.
>The spectral spillover into FL2 (rpe) also shows a concomittant increase.
>We have a four PMT Coulter XL with System II software.
>We currently use Caltag's "Fix and Perm" with Mu and HT6 TdT clone from Dako.
>We did see it once with our previous "in house" permeablisation method but it
>never repeated itself.
>
>Any ideas ?
>
>Wal Sharp
>SQU
>Oman.
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