The effects of dexamethasone on rituximab-induced ADCC.

▪ indicates dexamethasone, 0 μM; ░, dexamethasone, 10 μM. (A) ADCC with dexamethasone, rituximab, and effector cells simultaneously. All cell lines tested were sensitive to rituximab-mediated ADCC. The addition of a clinically relevant dose of dexamethasone to rituximab simultaneously did not significantly alter specific lysis in any cell line. This is representative of 2 experiments performed. (B) ADCC with dexamethasone: pretreatment of target cells. ADCC following preincubation of target cells with dexamethasone (10 μM for 48 hours) resulted in increased lysis in 5 B-NHL cell lines. This is representative of 2 experiments performed. Error bars represent SD of the mean. Asterisks represent statistically significant 2-tailed P values with the use of the Student t test of independent samples. *P < .005; **P < .0001. (C) ADCC with dexamethasone: pretreatment of effector cells. ADCC assays performed following preincubation of effector cells with dexamethasone (10 μM for 48 hours) resulted in significant impairment of ADCC in all B-NHL cell lines tested. This is a representative Figure of 2 experiments performed. (D) ADCC: pretreatment of effector and target cells with dexamethasone. ADCC assays performed following preincubation of both effector and target cells with dexamethasone (10 μM for 48 hours) resulted in significant impairment of ADCC in 4 B-NHL cell lines, whereas ADCC in the remaining 3 cell lines were not significantly impaired. Asterisks represent statistically significant 2-tailedP values with the use of the Student t test of independent samples. *P < .05. This is representative of 2 experiments performed.