Establishment and characterization of a novel ALL-L3 cell line (BALM-18): induction of apoptosis by anti-IgM and inhibition of apoptosis by bone marrow stroma cells.

A human acute lymphoblastic leukemia (ALL) cell line, BALM-18, was established from the peripheral blood specimen of a patient with B cell ALL L3 type (ALL-L3) at diagnosis using bone marrow stroma cells (BST) as feeder cells. The primary leukemia cells did not grow without feeder cells. As with the primary leukemia cells, BALM-18 showed an immunophenotype of Burkitt's lymphoma group I [CD10+, CD20+, CD23-, CD39-, CD77+] and carried the t(8;14)(q24;q32) chromosomal abnormality which is highly associated with ALL-L3 and Burkitt's lymphoma. It also revealed a significantly low level of bcl-2 protein. Strikingly, anti-human IgM antibody did induce apoptosis in induction experiments. However, it was reversed by the addition of anti-CD40 antibody or BST cells, whereas the culture supernatant of the stroma cells did not show any effect on the inhibition of apoptosis. BALM-18 may be useful for analyzing both the mechanisms of anti-IgM induced apoptosis and signaling during the inhibition of apoptosis by CD40 or BST cells.