ZAP-70 Expression Is Low in Normal Precursor B Cells

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Cytometry B Clin Cytom. 2006 Aug 11;70B(4):314-318

ZAP-70 expression is low in normal precursor B cells or

hematogones*. BH, Schwartz M.

U.S. Labs, Irvine, California.

BACKGROUND:: Zeta-associated protein (ZAP-70) expression has been

associated with a less favorable prognosis in chronic lymphocytic

leukemia (CLL). The role of ZAP-70 in immature B-cells is not well

understood. Immature or precursor B lymphocytes (hematogones) often

occur in clinical samples and coexpress CD10, CD38, and CD19 lacking

surface immunoglobulin expression. The present study was carried out

in an attempt to further elucidate the role of ZAP-70 in the spectrum

of B-cells seen in clinical specimens.

METHODS:: ZAP-70 expression was evaluated on 25 patient samples that

expressed greater than 2% of CD10(+)/CD38(bright)/CD19(+)

coexpression during routine evaluation. In our sample set, the

hematogone expression ranged from 2 to 18% of total leukocytes and

occurred in a variety of conditions, including CLL, NHL, AML, MDS,

Hodgkins Disease, and Multiple Myeloma. The method of ZAP-70

detection was that routinely applied to our clinical testing of CLL

samples supplemented with the determination of ZAP-70 levels in the

CD38(bright)/CD19(+) coexpressing cells.

RESULTS:: In all cases ZAP-70 was not expressed on the CD5 negative,

CD38/CD19 coexpressing precusor B cells. In all cases hematogones

were found to not express significant levels of ZAP-70.

CONCLUSION:: The presence of hematogones in clinical samples should

be recognized so as to not adversely influence prognostic studies of

ZAP-70 or CD38 in CLL.

© 2006 International Society for Analytical Cytology.

PMID: 16906572 [PubMed - as supplied by publisher]

*A type of immature B lymphocytes. These cells may look like

cancerous cells, but are not.