B-lineage leukemic cell viability is enhanced during Ara-C or VP-16 treatment by bone marrow stromal cells.

(A) JM-1 cells were cultured in medium alone or with an adherent layer of bone marrow stromal cells for 24 to 72 hours in the presence or absence of Ara-C or (B) VP-16 at indicated concentrations. Leukemic cells were removed by vigorous pipetting, and viability was evaluated by trypan blue exclusion in triplicate samples. Data shown are representative of 4 independent experiments. (C) RS4, SUP B-15, or Jurkat cells were cultured for 48 hours in medium containing 0.1 μg/mL Ara-C (solid black bars) or 1 μmol/L VP-16 (open bars). Leukemic cells were treated with the same concentration of Ara-C (hatched bars) or VP-16 (light gray bars) during coculture with an adherent layer of bone marrow stromal. Leukemic cells were removed by vigorous pipetting, and viability was evaluated as above. Data shown are mean ± SEM and are representative of 2 independent experiments.