Flow cytometric analysis for TRAIL receptor expression in MM cell lines.

Flow cytometric analyses for surface TRAIL receptors' expression in 5 representative cell lines (the TRAIL-sensitive MM-1S and RPMI-8226/S cells and the TRAIL-resistant ARH-7, IM-9, and HS Sultan cells) indicates that the status of neither the TRAIL-signaling DR4 and DR5 nor the “decoy” DcR1 and DcR2 receptors can serve to predict the TRAIL sensitivity of MM cells. The depicted graphs were obtained after staining with antihuman DR4, DR5, DcR1, and DcR2 mAbs (Genentech) and confirmed by use of the other anti-TRAIL receptor antibodies described in “Materials and methods.” Shaded curves depict isotype control staining, and unshaded peaks correspond to staining with the respective TRAIL receptor antibodies.