ZAP-70 Expressing in Portion of Normal, Activated Lymphocytes

[Guest guest]

[interesting finding. Could more aggressive CLL come from these

cells?]

Leukemia. 2005 Mar 31; [Epub ahead of print]

ZAP-70 is expressed by a subset of normal human B-lymphocytes

displaying an activated phenotype.

Nolz JC, Tschumper RC, Pittner BT, Darce JR, Kay NE, Jelinek DF.

1Department of Immunology, Mayo Clinic College of Medicine, Mayo

Graduate School, Rochester, MN, USA.

The Syk family tyrosine kinase ZAP-70 is essential for normal T-cell

development and signaling. Recently, leukemic cells from some

patients with B-cell chronic lymphocytic leukemia (B-CLL) were shown

to express ZAP-70.

Owing to the prognostic value of B-CLL ZAP-70 expression, this

phenotype may reflect intrinsic biological differences between the

two subsets of disease. However, it remains unclear whether CLL-B

cells aberrantly acquire ZAP-70 expression during the transformation

process or whether ZAP-70 may be expressed under certain conditions

in normal human B-lymphocytes.

To discriminate between these two possibilities, we assessed ZAP-70

expression in normal human B-lymphocytes. Our data demonstrate that

ZAP-70 is expressed in a subpopulation of tonsillar and splenic

normal B-lymphocytes that express an activated phenotype.

Furthermore, ZAP-70 expression can be induced in vitro upon

stimulation of blood and tonsillar B cells. Finally, we show that

phosphorylation of ZAP-70 occurs in tonsillar B cells with

stimulation through the B-cell receptor. These results provide new

insight into normal human B-cell biology as well as provide clues

about the transformed cell in B-CLL.

Leukemia advance online publication, 31 March 2005;

doi:10.1038/sj.leu.2403726.

PMID: 15800671 [PubMed - as supplied by publisher]