Modulation of proapoptotic and antiapoptotic Bcl-2 family proteins by rituximab in Ramos RA1 cells. (A) Flow cytometric analysis of Bcl-2 levels in NHL cell lines. Data are reported as MFI. The background fluorescence for the isotype control antibody on all cell lines was an MFI less than 6. (B) Immunoblot analysis of Bcl-2 expression in NHL cell lines. (C,D) Effect of Bcl-2 overexpression in Ramos RA1 cells on caspase-3 activation. Flow cytometric analyses of active caspase-3–positive Ramos RA1 cells treated with rhApo2L/TRAIL alone (•) or rhApo2L/TRAIL and rituximab (20 μg/mL, ■) for 24 hours. (E,F) Effect of Bcl-2 overexpression in Ramos RA1 cells on loss of mitochondrial-membrane integrity. Flow cytometric analyses of DiIC1(5)-negative Ramos RA1 cells treated with vehicle (◇), rhApo2L/TRAIL (1 μg/mL, ○), rituximab (20 μg/mL, ▴), or rhApo2L/TRAIL and rituximab (■). Cells were analyzed for DiIC1(5) at the indicated number of hours after addition of rhApo2L/TRAIL.
