A robust ratio metric method for analysis of Zap-70 expression in chronic lymphocytic leukemia (CLL)

Antony C. Bakke, Zoe Purtzer, Jose Leis, James Huang

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

Since Zap-70 expression in chronic lymphocytic leukemia (CLL) cells correlates with a lack of somatic mutation of the immunoglobulin variable heavy chain (IgVH) genes, it has been proposed as a surrogate marker for disease prognosis. However, published studies of Zap-70 expression have used different commercial antibodies and analytic strategies. This study was undertaken to determine if any strategy was broadly applicable in a clinical flow cytometry laboratory. Expression of Zap-70 was determined in 37 CLL patients using four different commercial antibodies. T, NK, and CLL cells were identified by immunophenotyping along with Zap-70 expression. Data was analyzed in terms of both percent of CLL cells expressing Zap-70 and the ratio of Zap-70 expression in CLL cells compared to that in T + NK cells. Three Zap-70 antibodies showed wide ranges of Zap-70 expression as a percentage of tumor cells, while a fourth gave consistently elevated results. Comparing the percent Zap-70 expression with any two antibodies gave poor correlations (r2 = 0.45-0.63). Our results indicated that the previous analytical strategies were not reproducible. A ratio metric is proposed, which gave better correlations (r2 as high as 0.95) and would allow separation of CLL patients with elevated or decreased Zap-70 expression.

Original languageEnglish (US)
Pages (from-to)227-234
Number of pages8
JournalCytometry Part B - Clinical Cytometry
Volume70
Issue number4
DOIs
StatePublished - Jul 15 2006

Keywords

  • Chronic lymphocytic leukemia
  • Flow cytometry
  • Prognosis
  • Zap-70

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Cell Biology

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