CD38⁺/ZAP-70⁺ CLL cells show enhanced migration in response to SDF-1α. (A) PBMCs from 38 patients with CLL were assayed in the bare-filter chemotaxis assay for migration toward SDF-1α (100 ng/mL). The comparison between CD38⁺ (n = 15) and CD38⁻ (n = 14) patients (▩) or between ZAP-70⁺ (n = 15) and ZAP-70⁻ (n = 15) patients (□) is not statistically significant. On the contrary, the results scored by comparing CD38⁺/ZAP-70⁺ (n = 11) with CD38⁻/ZAP-70⁻ (n = 11) or with CD38⁺/ZAP-70⁻ (n = 8) patients (■) are significantly different. Results are expressed as the mean of the migration indexes, while the error bars indicate the SEM. Statistical difference was calculated according to the Student 2-sample, 2-tailed t test. (B) MFI values for CXCR4 expressed by the 38 patients studied for migration. The comparison between CD38⁺ (n = 23) and CD38⁻ (n = 16) () is not statistically significant, as opposed to the results scored by comparing ZAP-70⁺ (n = 17) with ZAP-70⁻ (n = 22) patients (◇) and CD38⁺/ZAP-70⁺ (n = 13) with CD38⁻/ZAP-70⁻ (n = 14) patients (◆). CD38⁺/ZAP-70⁻ patients (n = 8) featured CXCR4 MFI values not significantly different from CD38⁻/ZAP-70⁻ patients. (C) Migration was completely abrogated by anti (α)–CXCR4 treatment. Pretreatment with the irrelevant anti (α)–gp120 mAb excluded a nonspecific block. Results are presented as percentage of inhibition of migration in the absence of antibodies and are the means plus or minus SEM of 5 experiments.