Analysis of ZAP70 expression in adult acute lymphoblastic leukaemia by real time quantitative PCR

Background: ZAP70 gene expression is associated with poor prognosis in B-cell lymphoproliferative disorders especially chronic lymphocytic leukaemia (CLL) but its role in adult B-ALL has not been established. On diagnostic samples from 76 patients with adult ALL (65 with B-ALL and 11 with T-ALL) ZAP70 mRNA expression levels were studied by real time-quantitative PCR (RT-qPCR) analysis. Findings: A broad distribution of ZAP70 expression was observed in ALL, ranging from 0.002 to 5.3 fold that of the ZAP70 positive Jurkat reference cell line. No association was observed between expression levels and the presence of specific cytogenetic abnormalities. Five cases, including one case of T-ALL, had ZAP70 expression above the level of the Jurkat reference cell line. Conclusions: Our results confirm the frequent expression of ZAP70 in adult ALL. Limited comparisons made did highlight poor-risk patients with high ZAP70 expression, but due to lack of clinical information on patient samples we were unable to directly assess the impact on disease prognosis. ZAP-70 may be an important laboratory assay in adult ALL and further studies are warranted to study a potential correlation with cytogenetic and other genetic markers.