Effects of neutralizing antibodies on the apoptosis of B-CLL cells supported by the ECCM.

B-CLL cells were incubated with CM, ECCM, or ECCM preincubated with anti–GM-CSF (A) or anti–IL-6 neutralizing antibodies (B), which sufficiently neutralize 40 ng GM-CSF and 5 ng IL-6, respectively. The dose-dependent inhibition mediated by anti–IL-6 antibodies is shown. ECCM was also preincubated with IgG (100 μg/mL) from preimmune rabbit serum as a control for nonspecific antibody effects. Percentages of apoptotic cells were measured in a 48-hour assay.