TdT caveat

From: Walter Sharp (denby@compuserve.com)
Date: Fri Apr 18 1997 - 00:14:04 EST


Following earlier discussions re: Caltag and, perhaps, tying in to the more
recent TdT neg ALL exchanges we also had an apparently negative T-ALL
(2/cy3/5/7/8/34) the other day.
I say apparent because a repeat of the staining using our in house method
gave a clear (admittedly dim) TdT positive result where the HT6 clone in
Fix & Perm was unequivocally (0%) negative.Both methods were whole blood
using identical concentrations & timings.
The strength of the cytoplasmic CD3 staining was the same by both
techniques so it appears that the nuclear membrane may be a little too
tough for An der Grubb's stuff.
As I said way back when, I have always been suspicious of the strength of
Caltag TdT staining but I didn't expect such a big disagreement between
methods.
In future all our TdT staining (tho' not MPO!) will be by our own method -
we just have to sort out the higher autofluorescence seen with AML's after
fixation (must re-read the postings on this).

Since I'm on about TdT, what do other contributors feel about setting the
positive region ?
Matched isotypic, unstained control, TdT staining on normal lymphs or what
?

Wal Sharp
SQU
Oman



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