CD27 in B-cell chronic lymphocytic leukemia. Cellular expression, serum release and correlation with other soluble molecules belonging to nerve growth factor receptors (NGFr) superfamily

Abstract

BACKGROUND AND OBJECTIVE: CD27, a transmembrane homodimer belonging to the nerve growth factor (NGF) receptor superfamily, is typically expressed on leukemic CD5+ cells in B-cell chronic lymphocytic leukemia (CLL) and found in soluble form in the serum of CLL patients. Therefore, we investigated clinico-biological implications of increased serum levels of sCD27 in an unselected series of B-CLL patients. DESIGN AND METHODS: Serum CD27 (sCD27) levels were determined at the time of diagnosis in 82 previously untreated B-CLL patients using a sandwich enzyme-linked immunoassay (ELISA). Results were correlated with either clinico-hematological or biological features. Finally, quantitative flow cytometric analyses of membrane CD27 (mCD27) expression were carried out on peripheral blood (PB) cells of 22 B-CLL patients and 5 healthy controls, respectively. RESULTS: CD27 was found to be expressed on the surface of both resting normal and leukemic B cells. sCD27 levels were significantly higher in B-CLL patients (median value 2150 U/mL) than in healthy controls (median value 220 U/mL) (p < 0.0001). There was a close relationship between sCD27 and soluble TNF-alpha, another molecule belonging to the NGF receptor superfamily. Changes in sCD27 level correlated with clinical stage, beta 2 microglobulin and LDH. INTERPRETATION AND CONCLUSIONS: These findings indicate that sCD27 is a reliable marker of tumor mass in B-CLL. Its potential prognostic value should be tested in prospective studies.