Correlative Study of ZAP-70 Gene Expression by Quantitative PCR and CD-38 Surface Marker in Patients with Chronic Lymphocytic Leukemia (CLL).

Patients with chronic lymphocytic leukemia have heterogeneous clinical courses. Many possible prognostic factors have been evaluated as a way to predict each patient’s future course. Two such prognostic factors are IgVH gene mutational status and CD38 expression. Recently, ZAP-70 expression has been found to correlate with IgVH gene mutation, but little is known about the correlation between ZAP-70 and CD 38 expression. We sought to evaluate the concordance between the two. METHODS: A procedure was developed at our institution to evaluate ZAP-70 transcripts by PCR. The results were then confirmed by flow cytometry. The blood or bone marrow samples of 14 patients diagnosed with CLL were analyzed by PCR for ZAP-70 transcripts and flow cytometry for ZAP-70 protein expression and CD38 expression. The results of the ZAP-70 transcripts and CD38 expression were then correlated to the clinical courses of the patients. RESULTS: Of the 14 patients analyzed, the majority had Rai Stage I disease at diagnosis (4 Stage 0, 8 Stage I, and 2 Stage II). There was a median follow-up of 28 months. The median number of treatments for these patients was one (range 0–6). Overall, the results for ZAP-70 and CD38 expression were concordant in eight with CD38 data unavailable for 2 patients. In the four patients with discordant results, 3 of them had high CD38 expression and low ZAP-70. However, patients with high ZAP-70 were more likely to require multiple treatments once treatment was indicated. Patients with high CD38 were also more likely to be treated. Cytogenetic data was available for 9 patients with the following results: 5 with normal cytogenetics, 1 with deletion of 11q, 1 with deletion of 13q, and 2 with deletion of 17p. Five of the nine patients had high ZAP-70 expression. CONCLUSIONS: In our institution, the results of ZAP-70 and CD38 expression were concordant 67% of the time. Longer follow-up is necessary and may further delineate the roles of cytogenetics, ZAP-70 expression, and CD38 expression on prognosis in CLL.