Upstream mediators of the Fas apoptotic transduction pathway are defectivein B-chronic lymphocytic leukemia

Data concerning the presence and the functionality of Fas receptor in malig nant B-cells are controversial. We have analyzed Fas molecules on B-cells f rom patients with B-chronic lymphocytic leukemia (B-CLL) cells. We observed a large variability, both of percentage of Fas-positive cells and of inten sity of Fas level. Fas triggering was inefficient in inducing apoptosis wha tever the number of Fas-positive B-cells, the amount of Fas receptors. B-ce lls were also resistant to etoposide treatment, but able to undergo apoptos is after dexamethasone treatment, We suggest that the Fas apoptotic pathway is altered in B-CLL patients at the initial step(s) of apoptotic machinery . (C) 2001 Elsevier Science Ltd. All rights reserved.