MV induces massive cell death in primary myeloma cells. Mononuclear cells from bone marrow, pleural effusion, or peripheral blood from patients with MM were stained with APC-CD138 and PE-control or PE-CD46 or PE-CD150 mAbs, and fluorescence was analyzed by flow cytometry. (A) Cells were incubated for 4 days with MV-GFP (MOI = 1). Cells were washed and stained with APC-CD138 mAb prior to flow cytometry analysis. GFP expression was assessed in CD138⁺ myeloma cells and CD138⁻ cells (FSC^low SSC^low CD138⁻). Myeloma cell death was assessed at day 4 by the loss of CD138 staining, as previously described.^30,31  (B) Anti-CD46 mAb prevented MV-GFP infection in primary cells. Prior to MV-GFP infection (performed as described in panel A), mononuclear cells were incubated for 2 hours with the blocking anti-CD46 mAb (final concentration, 10 μg/mL). GFP histograms represent GFP expression in noninfected cells (dashed line), in MV-GFP–infected cells (thin line), and in MV-GFP–infected cells in the presence of anti-CD46 mAb (thick line). (C) Myeloma cells with or without del(17p) were similarly sensitive to MV-GFP. The graphs represent the expression of CD46 and GFP. CD46 staining was assessed in double staining with anti-CD138 mAb before incubation with MV-GFP (MFIR, which was calculated by dividing the mean fluoresence intensity of specific staining over that of control staining). GFP expression was reported as the percentage of positive cells and the expression level (MFIR), which was the FL1 expression level in infected GFP-positive CD138⁺ cells over paired control samples. The statistical analyses were performed using the Mann-Whitney U test.