ZAP-70 in CLL: Is it reliable ?

Pál Jáksó pal.jakso at aok.pte.hu
Tue Jun 29 12:18:57 EST 2004


Dear Flowers,

I'm dealing with ZAP-70 staning in CLL cases. I use Caltag's ZAP-70 PE 
antibody. The literature says that T/NK cells should be used as marker 
of positivity but I've tested it with isotypic controll as well. In 
both cases the positivity is very weak. For example today tested ZAP-70 
with T-cells stained with ZAP-70 PE and compared to unstained cells. 
The intensity of the staining was very weak. The geometric mean of the 
ZAP-70 intensity of T cells is only  3 times bigger than the unstained 
cells, and there is a clear overlap between the two histograms. When I 
adjusted the lower marker bound to the left side of the peak on the 
ZAP70 stained T cells there was a huge overlap between the stained and 
unstained cells: about 70 % !!!!
I've seen publications which use 20% ZAP-70 positive cells as an 
artificial limit as prognostic criteria in CLL using the T cells as 
ZAP-70 markers but I'm very sceptical on these data.
Please share your experience and opninon of the usefulness of this test.

Thanks,

Pal Jakso

University of Pecs
Faculty of Medicine
Dept. of Pathology
12. Szigeti str.
H-7643 Pecs, HUNGARY




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