Angiogenesis has been recently extensively studied in a wide spectrum of hematological malignancies. Endoglin (CD105), member of transforming growth factor beta (TGF-beta) receptor family, modulates cellular responses to TGF-beta and is essential for angiogenic processes. Elevated circulating levels of soluble endoglin (sCD105) have been reported in patients with various solid tumors and several hematological malignancies. In the present study, we measured peripheral blood plasma concentrations of sCD105 using enzyme-linked immunosorbent assay in 79 patients with chronic lymphocytic leukemia and 69 healthy donors. We found a statistically significant increase in sCD105 concentrations in patients with CLL compared to controls (mean ± standard deviation: 6.8 ± 2.1 vs. 4.6 ± 1.5 ng/ml, 95% confidence interval of mean: 6.4-7.3 vs. 4.2-4.9 ng/ml, p<0.0001). Patients with progressive CLL had higher sCD105 than patients with indolent disease (p=0.0016). Soluble endoglin increased significantly with Rai stage (Rai 0 vs. I-II vs. III-IV, p=0.009 and p=0.04). Progression-free survival was significantly shorter in patients with sCD105 levels above mean (median 15 months vs. not reached, p=0.0045). In conclusion, our data suggest that endoglin may play a significant role in CLL biology and progression; its quantification could contribute to better understanding of angiogenic processes and refine prognostication of individual patients in this disease.

        Key words: endoglin, CD105, angiogenesis, CLL, prognosis