The effects of dexamethasone on rituximab-induced CDC.

(A) Simultaneous dexamethasone and rituximab exposure. CDC was measured in cells following exposure to non–heat-inactivated human (AB) serum and rituximab. Cells were treated with human serum and rituximab (5 μg/mL), with and without dexamethasone (10 μM). There was no significant difference in CDC observed in 9 B-NHL cell lines by the addition of dexamethasone. This is a representative example of 2 experiments. (B) The effects of dexamethasone pretreatment on rituximab-induced CDC. Pretreatment of 3 B-NHL cells with dexamethasone resulted in significantly increased sensitivity to complement-mediated lysis: DHL-4 (46% to 75%, P < .001); Fl-18 (56% to 71%, P = .003); and Tab (41% to 73%,P = ≤ .0001). Specific lysis for samples (n = 6) were compared with the control by means of the Studentt test for independent samples. This is representative of 3 experiments.