Growth inhibition.

(A) Growth inhibition by rituximab. The growth-inhibitory effect of rituximab on B-NHL cell lines was measured by means of a 96-hour growth assay by quantitating tritiated thymidine incorporation. Results are shown as counts per minute. Rituximab treatment (0 to 10 μg/mL) results in dose-dependent growth inhibition in these 7 B-NHL cell lines. P values are 2 sided, comparing the treatment group with the control for 3 samples, obtained from the Student ttest of independent samples: *P < .05; **P < .01; ***P < .001. This figure is representative of at least 3 experiments. (B) Growth inhibition by rituximab and dexamethasone. Dexamethasone dose-response curves in the presence of rituximab were evaluated by means of growth inhibition assays. Results are expressed as counts per minute divided by control. In 6 malignant B-cell lines, the dexamethasone dose-response curve is steeper and/or shifted to the left in the presence of rituximab, suggesting synergistic growth inhibition between the 2 agents. This figure is representative of at least 3 experiments. (C) Growth inhibition by dexamethasone is inhibited by RU-486. Growth inhibition of dexamethasone alone (▪); dexamethasone with rituximab (●); dexamethasone and RU-486 (▴); and dexamethasone, rituximab, and RU-486 (♦) is shown. RU-486 does not inhibit the dose-dependent growth inhibition by rituximab alone.